Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Rollforward of stock options Share-based Compensation, Stock Options, Activity [Table Text Block] Rollforward of nonvested restricted shares and restricted stock units Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Future stock-based compensation expense Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block] Income Tax Disclosure [Abstract] Deferred tax liabilities Deferred Tax Liabilities, Gross [Abstract] Property and equipment Deferred Tax Liabilities, Property, Plant and Equipment Net unrealized holding gains recognized in income Deferred Tax Liabilities, Net Unrealized Holding Gains Recognized in Income Deferred Tax Liabilities, Net Unrealized Holding Gains Recognized in Income Net unrealized holding gains on investments held as available-for-sale Deferred Tax Liabilities, Other Comprehensive Income Other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Gross Deferred tax assets Deferred Tax Assets, Gross [Abstract] Stock-based compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Asset impairments Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Impairment Losses Accrued compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation Supplemental savings plan Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Deferred Compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Deferred Compensation Currency translation adjustment Deferred Tax Assets, Other Comprehensive Loss Other Deferred Tax Assets, Other Total deferred tax assets Deferred Tax Assets, Gross Net deferred tax asset Deferred Income Tax Assets, Net Property, Plant and Equipment [Abstract] PROPERTY AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Property and equipment Deferred Income Tax Expense (Benefit), Related to Property and Equipment Deferred Income Tax Expense (Benefit), Related to Property and Equipment Stock-based compensation Deferred Income Tax Expense (Benefit), Related to Stock-Based Compensation Deferred Income Tax Expense (Benefit), Related to Stock-Based Compensation Accrued compensation Deferred Income Tax Expense (Benefit), Related to Accrued and Deferred Compensation Deferred Income Tax Expense (Benefit), Related to Accrued and Deferred Compensation Supplemental savings plan liability Deferred Income Tax Expense (Benefit), Related to Compensation and Benefits, Deferred Compensation Deferred Income Tax Expense (Benefit), Related to Compensation and Benefits, Deferred Compensation Other-than-temporary impairments of available-for-sale investments Deferred Income Tax Expense (Benefit), Related to Other-Than-Temporary Impairments of Available-for-Sale Investments Deferred Income Tax Expense (Benefit), Related to Other-Than-Temporary Impairments of Available-for-Sale Investments Unrealized holding gains recognized in non-operating income Deferred Income Tax Expense (Benefit), Related to Unrealized Holding Gains Recognized in Income Deferred Income Tax Expense (Benefit), Related to Unrealized Holding Gains Recognized in Income Other Deferred Income Tax Expense (Benefit), Related to Other Deferred Income Tax Expense (Benefit), Related to Other Total deferred income taxes (tax benefits) Deferred Income Tax Expense (Benefit) Consolidated Sponsored Investment Portfolios [Abstract] Consolidated Sponsored Investment Portfolios [Abstract] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Consolidated T. Rowe Price investment products [Member] Consolidated Investment Portfolios [Member] Consolidated Investment Portfolios [Member] Voting interest entities [Member] Voting Interest Entities [Member] Voting Interest Entities [Member] Variable interest entities [Member] Variable Interest Entity, Primary Beneficiary [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable entities [Member] Reportable Legal Entities [Member] Consolidation eliminations [Member] Consolidation, Eliminations [Member] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products Effect of Exchange Rate on Cash and Cash Equivalents Net change in cash and cash equivalents during period Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of year Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current Income Tax Expense (Benefit), Continuing Operations [Abstract] U.S. federal Current Federal Tax Expense (Benefit) State and local Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Deferred income taxes (tax benefits) Total Income Tax Expense (Benefit) Organization, Consolidation and Presentation of Financial Statements [Abstract] SUPPLEMENTARY CONSOLIDATING CASH FLOW STATEMENT Condensed Financial Statements [Text Block] Investments, Debt and Equity Securities [Abstract] Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions [Abstract] Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions [Abstract] Number of holdings with unrealized holding losses less than 12 months (number of securities) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year Number of holdings with unrealized holding losses 12 months or more (number of securities) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Total number of holdings with unrealized holding losses (number of securities) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] Unrealized holding losses of holdings that were in a continuous loss for less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Unrealized holding losses of holdings that were in a continuous loss for 12 months or more Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total unrealized holding losses of holdings that were in a continuous loss Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] Aggregate fair value of holdings with unrealized holding losses for less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Aggregate fair value of holdings with unrealized holding losses for 12 months or more Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Total aggregate fair value of holdings with unrealized holding losses Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Cash and cash equivalents Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] T.Rowe Price U.S. mutual funds [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Cash and cash equivalents Investments Investments Other assets Other Assets Total assets Assets Liabilities Liabilities Net assets Net Assets Attributable to redeemable non-controlling interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Attributable to T. Rowe Price Group Investment, Sponsored Investment Portfolios, Attributable to Parent Represents the reporting entity's interest in consolidated sponsored investment portfolios. This amount is eliminated in consolidation. Rental expense Operating Leases, Rent Expense Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Future minimum operating lease payments, due in 2018 Operating Leases, Future Minimum Payments Due, Next Twelve Months Future minimum operating lease payments, due in 2019 Operating Leases, Future Minimum Payments, Due in Two Years Future minimum operating lease payments, due in 2020 Operating Leases, Future Minimum Payments, Due in Three Years Future minimum operating lease payments, due in 2021 Operating Leases, Future Minimum Payments, Due in Four Years Future minimum operating lease payments, due in 2022 Operating Leases, Future Minimum Payments, Due in Five Years Future minimum operating lease payments, due in later years Operating Leases, Future Minimum Payments, Due Thereafter Unusual or Infrequent Items, or Both [Abstract] DELL APPRAISAL RIGHTS MATTER Unusual or Infrequent Items, or Both, Disclosure [Text Block] Cash and Cash Equivalents [Abstract] Cash equivalent investments in T. Rowe Price money market mutual funds Money Market Funds, at Carrying Value Restrictions on Cash and Cash Equivalents [Table] Restrictions on Cash and Cash Equivalents [Table] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Money market mutual funds [Member] Money Market Funds [Member] Restricted Cash and Cash Equivalents Items [Line Items] Restricted Cash and Cash Equivalents Items [Line Items] Dividends earned on money market mutual funds Investment Income, Dividend Supplementary consolidating cash flow statement Condensed Cash Flow Statement [Table Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Compensation and related costs [Member] Compensation and Related Costs [Member] Compensation and Related Costs [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted shares and restricted stock units [Member] Restricted Stock And Restricted Stock Units [Member] Shares and stock units that an entity has not yet issued because the agreed-upon consideration, such as employee services, has not yet been received. Restricted shares [Member] Restricted Stock [Member] Restricted stock units [Member] Restricted Stock Units (RSUs) [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Time-based [Member] Share-based Compensation Award, Tranche One [Member] Performance-based [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Nonvested at December 31, 2016 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Nonvested at December 31, 2017 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted-average fair value of nonvested restricted shares and restricted stock units at December 31, 2016 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted-average fair value of restricted shares and restricted stock units granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average fair value of restricted shares and restricted stock units vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted-average fair value of restricted shares and restricted stock units forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted-average fair value of nonvested restricted shares and restricted stock units at December 31, 2017 (in dollars per share) Value at vest date Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Nonvested shares where performance threshold has been met (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Performance Threshold Met, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Performance Threshold Met, Number Stock-based compensation expense Allocated Share-based Compensation Expense Vested stock units (in shares) Vested Restricted Stock Units The number of vested but unsettled awards (other than option plans) for which the company is obligated to issue equity instruments or transfer assets to a non-employee director. For these awards the non-employee director has satisfied the service or performance criteria necessary to gain title to the underlying shares but will not receive the shares until separation from the board. Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable interest entity, not primary beneficiary [Member] Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Investment carrying values Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Investment Carrying Values, Amount Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Investment Carrying Values, Amount Unfunded capital commitments Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Unfunded Capital Commitments, Amount Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Unfunded Capital Commitments, Amount Uncollected investment advisory and administrative fees Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Uncollected Investment Advisory and Administrative Fees, Amount Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Uncollected Investment Advisory and Administrative Fees, Amount Maximum risk of loss related to nonconsolidated variable interest entities Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Statement of Comprehensive Income [Abstract] Equity method investments [Member] Equity Method Investee [Member] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive income (loss) Other Comprehensive Income (Loss), before Tax [Abstract] Net unrealized holding gains (losses) on available-for-sale investments Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments and Tax Reclassification of (gains) and losses in accumulated other comprehensive income to non-operating investment income: Other Comprehensive Income (Loss), Available-For-Sale, Reclassification Adjustment From AOCI, Before Tax [Abstract] Other Comprehensive Income (Loss), Available-For-Sale, Reclassification Adjustment From AOCI, Before Tax [Abstract] Capital gain distributions Other Comprehensive Income (Loss) Adjustment For Capital Gain Distribution Received Before Tax 1 A positive value represents the before tax reduction in other comprehensive income upon reclassification of capital gain distributions included in non-operating income. Net gains realized on dispositions determined using average cost Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Net unrealized gains recognized upon the transfer to trading investments Other Comprehensive Income (Loss), Reclassification Adjustment From AOCI For Investment Transferred From Available-For-Sale To Trading Securities, Before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Trading Securities, before Tax Other-than-temporary impairments Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax Total reclassification adjustments Other Comprehensive Income (Loss) Reclassification Adjustment From AOCI For Available For Sale Securities Before Tax Amount before tax of all reclassification adjustments from accumulated other comprehensive income for unrealized gains (losses) related to available-for-sale securities. Total net unrealized holding losses recognized in other comprehensive income Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax Consolidated T. Rowe Price investment products—variable interest entities Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Reclassification losses (gains) recognized in non-operating investment income upon deconsolidation of certain T. Rowe Price investment products Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Total currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other comprehensive loss before income taxes Other Comprehensive Income (Loss), before Tax Net deferred tax benefits Other Comprehensive Income (Loss), Tax Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to redeemable non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to T. Rowe Price Group Comprehensive Income (Loss), Net of Tax, Attributable to Parent Accounting Policies [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent event [Member] Subsequent Event [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Net unrealized holding gains or losses [Member] Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Retained earnings [Member] Retained Earnings [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Pro forma [Member] Pro Forma [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2014-09 [Member] Accounting Standards Update 2014-09 [Member] ASU 2016-01 [Member] Accounting Standards Update 2016-01 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Reclassification of revenue related expenses to operating expenses Operating Expenses Reclassification of revenue related expenses from revenue to operating expenses Investment Advisory, Management and Administrative Fees Reclassification of unrealized holding gains recognized on investments from AOCI to retained earnings Stockholders' Equity Attributable to Parent Stockholders' Equity Note [Abstract] Impact of the components of other comprehensive income on deferred tax benefits (income taxes) Comprehensive Income (Loss) [Table Text Block] Changes in accumulated other comprehensive income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Basis of preparation - basis of accounting Basis of Accounting, Policy [Policy Text Block] Basis of preparation - use of estimates Use of Estimates, Policy [Policy Text Block] Newly issued but not yet adopted accounting guidance New Accounting Pronouncements, Policy [Policy Text Block] Consolidation Consolidation, Policy [Policy Text Block] Cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Available-for-sale sponsored investment portfolios Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block] Equity and cost method investments Equity and Cost Method Investments, Policy [Policy Text Block] Investments held as trading Marketable Securities, Trading Securities, Policy [Policy Text Block] Property and equipment Property, Plant and Equipment, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Revenue recognition Revenue Recognition, Policy [Policy Text Block] Advertising Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block] Stock-based compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Earnings per share Earnings Per Share, Policy [Policy Text Block] Comprehensive income Comprehensive Income, Policy [Policy Text Block] Statement of Financial Position [Abstract] Assets of consolidated T. Rowe Price investment products Variable Interest Entity, Consolidated, Carrying Amount, Assets Liabilities of consolidated T. Rowe Price investment products Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Stockholders' equity Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Common stock, shares issued (in shares) Common Stock, Shares, Issued Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Capital gain distributions [Member] Accumulated Net Investment Gain (Loss), Capital Gains (Losses) Distributions, Attributable to Parent [Member] Accumulated Net Investment Gain (Loss), Capital Gains (Losses) Distributions, Attributable to Parent [Member] Net gains realized on dispositions [Member] Accumulated Net Investment Gain (Loss), Net Gains (Losses) Realized on Dispositions of Securities, Attributable to Parent [Member] Accumulated Net Investment Gain (Loss), Net Gains (Losses) Realized on Dispositions of Securities, Attributable to Parent [Member] Net gains recognized upon transfer to trading investments [Member] Accumulated Net Investment Gain (Loss), Net Gains (Losses) Recognized on Transfer to Trading Securities, Attributable to Parent [Member] Accumulated Net Investment Gain (Loss), Net Gains (Losses) Recognized on Transfer to Trading Securities, Attributable to Parent Other-than-temporary impairments [Member] Accumulated Net Investment Gain (Loss), Other-Than-Temporary Impairments, Attributable to Parent [Member] Accumulated Net Investment Gain (Loss), Other-Than-Temporary Impairments, Attributable to Parent [Member] Currency translation adjustments [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Total accumulated other comprehensive income [Member] AOCI Attributable to Parent [Member] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of accumulated other comprehensive income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Non-operating income Nonoperating Income (Expense) Provision for income taxes Income tax provision related to the tax law changes Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Income tax provision related to remeasurement of deferred tax assets and liabilities Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit) Income tax provision related to mandatory deemed repatriation of foreign sourced net earnings Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit) Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair value, measurements, recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure T. Rowe Price investment products held as available-for-sale Available-for-sale Securities, Equity Securities T. Rowe Price investment products held as trading Trading Securities Total Assets, Fair Value Disclosure Unusual or Infrequent Item, or Both [Table] Unusual or Infrequent Item, or Both [Table] Gain Contingencies, Nature [Axis] Gain Contingencies, Nature [Axis] Gain Contingency, Nature [Domain] Gain Contingency, Nature [Domain] Dell appraisal rights matter [Member] Dell appraisal rights matter [Member] Dell appraisal rights matter[Member] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Line Items] Unusual or Infrequent Item, or Both [Line Items] Nonrecurring charge related to Dell appraisal rights matter Unusual or Infrequent Item, or Both, Loss, Gross Court determined fair value per share at time of Dell merger (in dollars per share) Court determined fair value per share The fair value per share of a company at the time of a merger that was determined by a court during the period. Price offered per share in Dell merger (in dollars per share) Price Offered, Per Share Price Offered, Per Share Payment per share for any shareholder perfecting appraisal rights (in dollars per share) Payment per share The amount per share that was determined to be paid to affected clients during the period which was intended to make them whole for the voting discrepancy that resulted in the denial of their appraisal rights. Insurance proceeds Unusual or Infrequent Item, or Both, Insurance Proceeds Unrecorded gain contingency Gain Contingency, Unrecorded Amount Earnings Per Share [Abstract] Earnings per share reconciliation Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Anti-dilutive securities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Other Disclosures [Abstract] Other Disclosures [Abstract] OTHER DISCLOSURES. Other Disclosures [Text Block] Other Disclosures [Text Block] Property and equipment summary Property, Plant and Equipment [Table Text Block] Net assets of consolidated T. Rowe Price investment portfolios Consolidated Sponsored Investment Portfolios Condensed Balance Sheet [Table Text Block] Tabular disclosure of condensed balance sheet for consolidated sponsored investment portfolios. Operating results of consolidated T. Rowe Price investment portfolios Consolidated Sponsored Investment Portfolios Condensed Income Statement [Table Text Block] Tabular disclosure of condensed income statement for consolidated sponsored investment portfolios. Cash flows of consolidated T. Rowe Price investment portfolios Consolidated Sponsored Investment Portfolios Condensed Cash Flow Statement [Table Text Block] Tabular disclosure of condensed cash flow statement of consolidated sponsored investment portfolios. Fair values of investments held by consolidated T. Rowe Price investment portfolios Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis for Consolidated Sponsored Investment Portfolios [Table Text Block] Tabular disclosure of assets and liabilities of consolidated sponsored investment portfolios that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). Schedules of provision for income taxes and deferred income taxes (tax benefits) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of effective income tax rate reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of unrecognized tax benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Income Statement [Abstract] Revenues Revenues, Net of Interest Expense [Abstract] Investment advisory fees Investment Advisory Fees Administrative fees Administrative Services Revenue Distribution and servicing fees Distribution Fees Net revenues Operating expenses Operating Expenses [Abstract] Compensation and related costs Labor and Related Expense Advertising and promotion Marketing and Advertising Expense Distribution and servicing costs Noninterest Expense Distribution and Servicing Fees Depreciation and amortization of property and equipment Depreciation, Nonproduction Occupancy and facility costs Occupancy and Facility Costs Amount of expense incurred related to occupancy and facility costs, including, but not limited to lease and rent expense, owned facilities expense, and maintenance contracts for owned facilities. Other operating expenses Other Cost and Expense, Operating Nonrecurring charge (insurance recoveries) related to Dell appraisal rights matter Unusual or Infrequent Item, or Both, Net of Insurance Proceeds Total operating expenses Net operating income Operating Income (Loss) Non-operating income Nonoperating Income (Expense) [Abstract] Net investment income on investments not consolidated Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Net investment income on consolidated T. Rowe Price investment products Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Other income (expense) Other Nonoperating Income (Expense) Total non-operating income Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Provision for income taxes Net income Less: net income attributable to redeemable non-controlling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Net income attributable to T. Rowe Price Group Net Income (Loss) Attributable to Parent Earnings per share on common stock of T. Rowe Price Group Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Information about Receivables, Revenues, and Services [Abstract] Information about Receivables, Revenues, and Services Revenue and Services [Table] Revenue and Services [Table] Summarization of information required and determined to be disclosed concerning advisory service revenues and the assets from which those revenues are derived, by customer and investment mandate. T. Rowe Price U.S. mutual funds [Member] Sponsored Mutual Funds In U S [Member] Sponsored mutual funds in the U.S. Revenue and Services [Line Items] Revenues and Services [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Administrative fees Distribution and servicing fees INFORMATION ABOUT RECEIVABLES, REVENUES, AND SERVICES Information About Receivables Revenues And Services Text Block This element is used to indicate facts reported for the continuing operations of a business entity including disclosure of receivables from sponsored mutual funds for both advisory fees and administrative services provided. This element also includes disclosure of the components of investment advisory fees and administrative fees earned as well as the components of average assets and period end assets under management. Statutory U.S. federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Impact of U.S. tax reform Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Percent Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Percent State income taxes for current year, net of federal income tax benefits Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Net income attributable to redeemable non-controlling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent Net excess tax benefits from stock-based compensation plans activity Effective Income Tax Rate Reconciliation, Share-Based Compensation, Excess Tax Benefits (Tax Shortfalls), Percent Effective Income Tax Rate Reconciliation, Share-Based Compensation, Excess Tax Benefits (Tax Shortfalls), Percent Other items Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent State income tax benefit related to redeemable non-controlling interests and stock-based compensation Effective Income Tax Rate Reconciliation, State and Local Income Taxes Reflected In Noncontrolling Interest Income (Loss) And Share-based Compensation, Percent Effective Income Tax Rate Reconciliation, State and Local Income Taxes Reflected In Noncontrolling Interest Income (Loss) And Share-based Compensation, Percent INVESTMENTS Investment [Text Block] Statement of Stockholders' Equity [Abstract] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] New accounting pronouncement, early adoption, effect [Member] New Accounting Pronouncement, Early Adoption, Effect [Member] Statement, Equity Components [Axis] Common stock [Member] Common Stock [Member] Additional capital in excess of par value [Member] Additional Paid-in Capital [Member] Retained earnings [Member] Retained Earnings, Unappropriated [Member] Accumulated other comprehensive income (loss) [Member] Accounting standards update 2015-2 [Member] Accounting Standards Update 2015-02 [Member] Accounting standards update 2016-9 [Member] Accounting Standards Update 2016-09 [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances (in shares) Shares, Outstanding Balances Cumulative effect of adopting new accounting guidance Cumulative Effect of New Accounting Principle in Period of Adoption Balances, Adjusted Stockholders' Equity Attributable to Parent, Adjusted Balance Amount of stockholders' equity attributable to parent, after the cumulative effect adjustment of a new accounting principle applied in the period of adoption. Net income Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Dividends declared Dividends, Cash Common stock-based compensation plans activity Stock Issued or Granted During Period, Share-based Compensation [Abstract] Shares issued upon option exercises (shares) Stock Issued During Period Stock Options Exercised Net Of Shares For Tax Withholding Strike Price A positive value represents the number of shares of stock issued during the period as a result of option exercises, net of shares withheld for the payment of withholding taxes and shares swapped for payment of strike price. Shares issued upon option exercises Stock Issued During Period Value Stock Options Exercised Net of Tax Withholdings Strike Price A positive value represents the value of stock issued as a result of the exercise of stock options less values of underlying shares swapped by the employee to pay the cost of the related stock option award and withheld to pay related income tax obligations. Shares issued, net of shares withheld for taxes (shares) Stock Issued During Period, Shares, Other Shares issued, net of shares withheld for taxes Stock Issued During Period, Value, Other Forfeiture of restricted awards (shares) Stock Issued During Period, Shares, Restricted Stock Award, Forfeited Forfeiture of restricted awards Stock Issued During Period, Value, Restricted Stock Award, Forfeitures Net tax benefits Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Stock-based compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Restricted stock units issued as dividend equivalents Dividends, Share-based Compensation, Paid-in-kind Common shares repurchased (shares) Stock Repurchased During Period, Shares Common shares repurchased Stock Repurchased During Period, Value Balances (in shares) Balances Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balances attributable to redeemable non-controlling interests Reclassification of T. Rowe Price investment products upon adoption of new accounting guidance on January 1, 2016 Cumulative Effect of New Accounting Principle in Period of Adoption, Redeemable Noncontrolling Interests Amount after tax of (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. Balances attributable to redeemable non-controlling interest, adjusted Redeemable Noncontrolling Interest, Equity, Carrying Amount, Adjusted Balance Redeemable Noncontrolling Interest, Equity, Carrying Amount, Adjusted Balance Net income attributable to redeemable non-controlling interests Other comprehensive loss, net of tax, attributable to reedemable non-controlling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Net subscriptions into T. Rowe Price investment products Subscription From Redemption Distribution To Noncontrolling Interest A positive value represents subscriptions net of redemptions and distributions to redeemable non-controlling interest holders of a less than wholly owned subsidiary. A negative value represents redemptions and distributions paid to redeemable non-controlling interest holders net of subscriptions received. Net deconsolidations of T. Rowe Price investment products Noncontrolling Interest, Decrease from Deconsolidation Ending balances attributable to redeemable non-controlling interests Quarterly Financial Information Disclosure [Abstract] SUPPLEMENTARY QUARTERLY FINANCIAL DATA (Unaudited) Quarterly Financial Information [Text Block] Investment Income [Table] Investment Income [Table] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Dividends excluding capital gain distributions [Member] Ordinary Dividend [Member] Ordinary Dividend [Member] Investments by Category [Axis] Investments by Category [Axis] Marketable Securities and Investments Held at Cost [Domain] Marketable Securities and Investments Held at Cost [Domain] Available-for-sale sponsored investment portfolios [Member] Available-for-sale Securities [Member] Net Investment Income [Line Items] Net Investment Income [Line Items] Dividends OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME Comprehensive Income (Loss) Note [Text Block] EARNINGS PER SHARE CALCULATIONS Earnings Per Share [Text Block] Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits, by Title of Individual and by Type of Deferred Compensation [Table] Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits, by Title of Individual and by Type of Deferred Compensation [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum [Member] Maximum [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Senior officers [Member] Executive Officer [Member] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Supplemental Savings Plan [Member] Deferred Bonus [Member] Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] Expense recognized for defined contribution retirement plans Defined Contribution Plan, Cost Deferral percentage of cash incentive compensation Deferred Compensation Arrangement with Individual, Cash Awards Granted, Percentage Deferred Deferred Compensation Arrangement with Individual, Cash Awards Granted, Percentage Deferred Supplemental Savings Plan, minimum deferral period Deferred Compensation Arrangement with Individual, Initial Minimum Contractual Term Deferred Compensation Arrangement with Individual, Initial Minimum Contractual Term Supplemental Savings Plan, maximum deferral period Deferred Compensation Arrangement with Individual, Initial Maximum Contractual Term Deferred Compensation Arrangement with Individual, Initial Maximum Contractual Term Amount of cash incentive compensation senior officers elected to defer Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Computer and communications software and equipment [Member] Computer And Communications Software And Equipment [Member] Long lived, depreciable assets used in the creation, maintenance, and utilization of information systems which include computers and peripherals, as well as capitalized costs of purchased software applications and capitalized costs to develop software for long-term internal use. Buildings and improvements [Member] Building and Building Improvements [Member] Leasehold improvements [Member] Leasehold Improvements [Member] Furniture and other equipment [Member] Furniture and Fixtures [Member] Leased land [Member] Leased Land [Member] Leased Land [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Estimated useful life Property, Plant and Equipment, Useful Life Fair value measurements summary Fair Value, Assets Measured on Recurring Basis [Table Text Block] Stockholders' Equity Note [Table] Stockholders' Equity Note [Table] Stockholders' Equity Note [Table] Regular cash dividend [Member] Special cash dividend [Member] Special Dividend [Member] Special Dividend [Member] Stockholders' Equity Note [Line Items] Stockholders' Equity Note [Line Items] [Line Items] for Stockholders' Equity Note [Table] Common shares authorized for future repurchase (shares) Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased Cash dividends declared per share Common Stock, Dividends, Per Share, Declared Cash dividends paid per share Common Stock, Dividends, Per Share, Cash Paid Restricted stockholders' equity Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by (used in) operating activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Stock-based compensation expense Share-based Compensation Realized gains on dispositions of available-for-sale T. Rowe Price investment products Available-for-sale Securities, Gross Realized Gains Gains recognized upon transfer of an investment in a T. Rowe Price mutual fund from available-for-sale to held as trading Available-for-sale Securities, Transfers to Trading, Gross Gains Net gains recognized on other investments Net Gains (Losses) Recognized on Investments Net Gains (Losses) Recognized on Investments Investments in T. Rowe Price mutual funds held as trading to economically hedge supplemental savings plan liability Proceeds from (Payments for) Trading Securities, Short-term Net change in trading securities held by consolidated T. Rowe Price investment products Increase (Decrease) In Trading Securities, Consolidated Sponsored Investment Portfolios Increase (Decrease) in Trading Securities, Consolidated Sponsored Investment Portfolios Changes in accounts receivable and accrued revenue Increase (Decrease) in Accounts Receivable Changes in payables and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Other changes in assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by (used in) operating activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of available-for-sale T. Rowe Price investment products Payments to Acquire Available-for-sale Securities, Equity Dispositions of available-for-sale T. Rowe Price investment products Proceeds from Sale of Available-for-sale Securities, Equity Net cash of T. Rowe Price investment products on consolidation (deconsolidation) Net Cash Flow For Consolidation Deconsolidation Of Sponsored Investment Portfolios The net cash inflow (outflow) associated with the consolidation (deconsolidation) of sponsored investment portfolios. Additions to property and equipment Payments to Acquire Property, Plant, and Equipment Other investing activity Payments for (Proceeds from) Other Investing Activities Net cash provided by (used in) investing activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Repurchases of common stock Payments for Repurchase of Common Stock Common share issuances under stock-based compensation plans Proceeds from stock options exercised, net of payments for repurchase of common stock for employee tax withholding obligations and strike price The cash inflow associated with the amount received from holders exercising their stock options net of 1) shares swapped by the employee to pay the cost of related employee stock option awards and 2) cash outflows paid by the company to cover an employee's income tax withholding obligation as part of a net-share settlement of a share-based award. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately. A positive value represents cash inflows in excess of cash outflows listed. A negative value represents cash outflows in excess of the cash inflow described. Dividends paid to common stock and equity-award holders Payments of Dividends Net subscriptions received from redeemable non-controlling interest holders Proceeds from (Payments to) Noncontrolling Interests Net cash (used in) provided by financing activities Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value, Including Consolidated Sponsored Investment Portfolios Cash and Cash Equivalents, at Carrying Value, Including Consolidated Sponsored Investment Portfolios Cash and cash equivalents at end of year Condensed Financial Statements [Table] Condensed Financial Statements [Table] Attributable to T. Rowe Price Group [Member] Consolidated Entities, Excluding Sponsored Investment Portfolios [Member] Consolidated Entities, Excluding Sponsored Investment Portfolios [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Realized gains on dispositions of available-for-sale sponsored investment portfolios Gains recognized upon transfer of an available-for-sale T. Rowe Price investment products to T. Rowe Price investment products held as trading Net gains recognized on investments Net cash provided by (used in) investing activities Unremitted earnings of foreign subsidiaries Undistributed Earnings of Foreign Subsidiaries Tax refund receivables Income Taxes Receivable Net income taxes paid Income Taxes Paid, Net Additional income tax benefit arising from stock-based compensation Employee Service Share Based Compensation, Excess Tax Benefit Realized From Exercise Of Stock Options Disclosure of the excess tax benefit realized relative to recognized stock-based compensation expense from the exercise of stock options and the conversion of similar instruments during the annual period. Prior to adoption of ASU 2016-9 excess tax benefits were recognized as a reduction of taxes payable and an increase to additional paid in capital. Net tax benefits reducing income tax provision Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit (Tax Shortfall), Amount Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit (Tax Shortfall), Amount Net interest payable related to unrecognized tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Income tax provision related to the tax law changes Net income attributable to T. Rowe Price Group Less: net income allocated to outstanding restricted stock and stock unit holders (basic) Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Less: net income allocated to outstanding restricted stock and stock unit holders (diluted) Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted Net income allocated to common stockholders (basic) Net Income (Loss) Available to Common Stockholders, Basic Net income allocated to common stockholders (diluted) Net Income (Loss) Available to Common Stockholders, Diluted Weighted-average common shares Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Outstanding assuming dilution (in shares) Weighted Average Number of Shares Outstanding, Diluted Weighted-average outstanding stock options excluded (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Stock compensation plan [Member] Stock Compensation Plan [Member] Employee stock purchase [Member] Employee Stock [Member] Shares of common stock authorized for issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Equity securities [Member] Equity Securities [Member] Fixed income securities [Member] Fixed Income Investments [Member] Other investments [Member] Other than Securities Investment [Member] Trading investments Liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Land [Member] Land [Member] Compensation and related costs attributable to the development of computer software for internal use [Member] Software Development [Member] Property and equipment, gross Property, Plant and Equipment, Gross Less accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Property, Plant and Equipment, Net Property and equipment, additions Property, Plant and Equipment, Additions STOCKHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Schedule of supplementary quarterly financial data Quarterly Financial Information [Table Text Block] Options [Member] Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Outstanding at December 31, 2016 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Expired (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period Outstanding at December 31, 2017 (in shares) Exercisable at December 31, 2017 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted-average exercise price of options outstanding at December 31, 2016 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted-average exercise price of options exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted-average exercise price of options forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Weighted-average exercise price of options expired (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Weighted-average exercise price of options outstanding at December 31, 2017 (in dollars per share) Weighted-average exercise price of options exercisable at December 31, 2017 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Weighted-average remaining contractual term in years, outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted-average remaining contractual term in years, exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Total intrinsic value of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Aggregate intrinsic value of in-the-money options outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value of options exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Net deferred tax benefits (income taxes) on other comprehensive income before reclassifications Other Comprehensive Income (Loss) before Reclassifications, Tax Net deferred tax benefits (income taxes) on reclassifications from AOCI Reclassification from AOCI, Current Period, Tax Total net deferred tax benefits (income taxes) Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS Consolidated Sponsored Investment Portfolios [Text Block] Consolidated Sponsored Investment Portfolios [Text Block] Concentration Risk [Table] Concentration Risk [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Outside U.S. [Member] Non-US [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Assets under management [Member] Assets Under Management [Member] Assets Under Management [Member] Investment advisory clients [Member] Investment Advisory Clients [Member] Investment Advisory Clients [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Geographic concentration [Member] Geographic Concentration Risk [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration risk, percentage Concentration Risk, Percentage INCOME TAXES Income Tax Disclosure [Text Block] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Stock and blended asset funds [Member] Equity Funds [Member] Bond funds [Member] Fixed Income Funds [Member] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Aggregate cost Available-for-sale Equity Securities, Amortized Cost Basis Unrealized holding gains Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax Unrealized holding losses Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax Aggregate fair value Number of distinct operating segments through which we internally conduct and manage our operations Number of Operating Segments Number of distinct operating segments through which we report our operations Number of Reportable Segments Number of reportable business segments and units to which goodwill is attributed (reporting unit) Number of Reporting Units Duration of fund holding unrealized loss between quarter-ends generally presumed to represent other than temporary impairment Available For Sale Equity Securities In Unrealized Loss Position, Qualitative Disclosure, Other Than Temporary Impairment Policy, Loss Term The period of time between quarter ends after which available-for-sale equity securities in a continuous unrealized loss position will generally be considered other than temporarily impaired under the company's impairment policy. ASSETS Assets [Abstract] Accounts receivable and accrued revenue Accounts Receivable, Net Assets of consolidated T. Rowe Price investment products ($1,446.1 million at December 31, 2016, and $1,839.6 million at December 31, 2017, related to variable interest entities) Property and equipment, net Goodwill Goodwill LIABILITIES Liabilities [Abstract] Accounts payable and accrued expenses Accounts Payable and Other Accrued Liabilities Liabilities of consolidated T. Rowe Price investment products ($56.8 million at December 31, 2016, and $39.5 million at December 31, 2017, related to variable interest entities) Accrued compensation and related costs Employee-related Liabilities Supplemental savings plan liability Deferred Compensation Arrangement with Individual, Recorded Liability Income taxes payable Accrued Income Taxes Total liabilities Commitments and contingent liabilities Commitments and Contingencies Redeemable non-controlling interests STOCKHOLDERS’ EQUITY Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, undesignated, $.20 par value— authorized and unissued 20,000,000 shares Preferred Stock, Value, Issued Common stock, $.20 par value—authorized 750,000,000; issued 244,784,000 shares at December 31, 2016, and 245,111,000 at December 31, 2017 Common Stock, Value, Issued Additional capital in excess of par value Additional Paid in Capital, Common Stock Retained earnings Retained Earnings, Unappropriated Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total permanent stockholders' equity Total liabilities, redeemable non-controlling interests and permanent stockholders’ equity Liabilities and Equity Financial Support to Nonconsolidated Legal Entity [Axis] Financial Support to Nonconsolidated Legal Entity [Axis] Financial Support to Nonconsolidated Legal Entity [Domain] Financial Support to Nonconsolidated Legal Entity [Domain] Waived money market related fees [Member] Financial Support, Waived Fees [Member] Other investment products [Member] Other Portfolios [Member] Other portfolios Other T. Rowe Price investment products [Member] Other Sponsored Investment Portfolios [Member] Other Sponsored Investment Portfolios [Member] Stock and blended asset [Member] Stock And Blended Asset [Member] Stock and blended asset [Member] Bond and money market [Member] Bond And Money Market [Member] Bond and money market [Member] Bond, money market, and stable value [Member] Bond Money Market And Stable Value [Member] Bond, money market and stable value [Member] Revenues from advisory services Average assets under management Assets under Management, Average Balance Period end assets under management Assets under Management, Carrying Amount SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] First quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter One Of Next Fiscal Year Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter One Of Next Fiscal Year Second quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Two Of Next Fiscal Year Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Two Of Next Fiscal Year Third quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Three Of Next Fiscal Year Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Three Of Next Fiscal Year Fourth quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Four Of Next Fiscal Year Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Four Of Next Fiscal Year Total 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Next Fiscal Year Unrecognized cost of unvested share-based compensation awards to be recognized in the next fiscal year. 2019 through 2023 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized From Second Fiscal Year to Vesting Unrecognized cost of unvested share-based compensation awards to be recognized in the second fiscal year through vesting period. Total Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Receivables from sponsored mutual funds Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts receivable for advisory fees and advisory-related administrative services FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Net unrealized holding gains [Member] Consolidated T. Rowe Price investment products - variable interest entities [Member] AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Reclassification of accumulated other comprehensive income to retained earnings upon adoption of the new consolidation accounting guidance Other comprehensive income (loss) before reclassifications and income taxes OCI, before Reclassifications, before Tax, Attributable to Parent Reclassification adjustments recognized in non-operating income Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Other comprehensive income (loss), before taxes Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Net deferred tax benefits (income taxes) Other comprehensive income (loss) Unconsolidated investments Investment [Table Text Block] Net impact of deconsolidation and consolidation on condensed consolidated balance sheets and income statements Schedule of Deconsolidation Impacts on Financial Statements [Table Text Block] Schedule of Deconsolidation Impacts on Financial Statements [Table Text Block] Available-for-sale T. Rowe Price investment products Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Continuous unrealized loss positions Schedule of Temporary Impairment Losses, Investments [Table Text Block] Maximum risk of loss related to investments in variable interest entities Schedule of Variable Interest Entities [Table Text Block] Assumptions used in option pricing model and grant date fair value of options Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance at beginning of year Unrecognized Tax Benefits Changes in tax positions related to current year Unrecognized Tax Benefits, Increase (Decrease) Resulting from Current Period Tax Positions Unrecognized Tax Benefits, Increase (Decrease) Resulting from Current Period Tax Positions Changes in tax positions related to prior years Unrecognized Tax Benefits, Increase (Decrease) Resulting from Prior Period Tax Positions Unrecognized Tax Benefits, Increase (Decrease) Resulting from Prior Period Tax Positions Changes in tax positions related to expired statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Balance at end of year Components of revenues from advisory services Components of Investment Advisory Fees [Table Text Block] Tabular disclosure of the components of revenue recognized in the period for schedule-based fees earned for management of mutual funds based on average daily net assets and other investment management and advisory fees earned on other client portfolios based on asset valuations. Components of assets under management Components of Assets Under Management [Table Text Block] Tabular disclosure of the components of average assets under management and period end assets under management. Assets under management represents the market value of assets an investment adviser manages on behalf of investors and is the basis for determining investment advisory fee revenue. Components of other fees Components Of Other Fees [Table Text Block] Tabular disclosure of the components of revenue recognized in the period for other fees earned from sponsored mutual funds in the United States. Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Employee stock-based compensation programs [Member] Employee Stock Based Compensation Programs [Member] Employee Stock-Based Compensation Programs Non-employee director plans [Member] Non Employee Director [Member] Non-employee director programs Stockholder-approved plans (plans) Stockholder Approved Plans For Stock Options The number of stockholder approved plans under which qualified incentive and nonqualified fixed stock options are granted. Shares available for future grant (shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Graded vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Term Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Grant-date fair value per option awarded (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Expected life in years Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Net revenues Net income Basic earnings on common stock (in dollars per share) Diluted earnings per share (in dollars per share) Investment [Table] Investment [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Assets [Member] Assets [Member] Liability [Member] Liability [Member] Redeemable non-controlling interest [Member] Redeemable Noncontrolling Interest [Member] The line item on the balance sheet representing the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity. Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] T. Rowe Price investment products [Member] Sponsored Investment Portfolios [Member] Sponsored Investment Portfolios [Member] T. Rowe Price investment products designated as an economic hedge of supplemental savings plan liability [Member] Sponsored Investment Portfolios Designated As Economic Hedge Of Supplemental Savings Plan Liability [Member] Sponsored Investment Portfolios Designated As Economic Hedge Of Supplemental Savings Plan Liability [Member] Interest in UTI Asset Management Company Limited (India) [Member] UTI Asset Management Company India [Member] UTI Asset Management Company India [Member] Investment partnerships [Member] Other Equity Method Investments [Member] Other equity method investments Investment [Line Items] Investment [Line Items] Equity method investments Equity Method Investments Cost method investments Cost Method Investments U.S. Treasury note Held-to-maturity Securities Total Equity method investment (ownership percentage) Equity Method Investment, Ownership Percentage Net increase (decrease) in assets, liabilities, and redeemable noncontrolling interest Deconsolidation Value2 Represents the carrying value of the assets (liabilities or redeemable noncontrolling interest) deconsolidated during the period as valued on the date that the parent no longer had a controlling financial interest in the subsidiary. Gains (losses) recognized upon deconsolidation Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Type Document Type Document Period End Date Document Period End Date Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Entity Registrant Name Entity Registrant Name Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding (shares) Entity Common Stock, Shares Outstanding Entity Central Index Key Entity Central Index Key Amendment Flag Amendment Flag CASH EQUIVALENTS Cash and Cash Equivalents Disclosure [Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Operating expenses Net investment non-operating income Investment Income, Nonoperating Net income attributable to T. Rowe Price Group Income (Loss) from Continuing Operations before Income Taxes, Attributable to Parent Income (Loss) from Continuing Operations before Income Taxes, Attributable to Parent Investment advisory and administrative fees