Property, Plant and Equipment [Abstract] PROPERTY AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Quarterly Financial Information Disclosure [Abstract] SUPPLEMENTARY QUARTERLY FINANCIAL DATA (Unaudited) Quarterly Financial Information [Text Block] 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. Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Investment advisory fees [Member] Asset Management [Member] Administrative fees [Member] Administrative Service [Member] Distribution and servicing fees [Member] Distribution Service [Member] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] T. Rowe Price U.S. mutual funds [Member] Sponsored Mutual Funds In U S [Member] Sponsored mutual funds in the U.S. Subadvised and separate accounts and other investment product [Member] Subadvised, Separate Accounts, And Other Investment Products [Member] Subadvised, Separate Accounts, And Other Investment Products [Member] Other clients [Member] Other Clients [Member] Other Clients [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] 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] 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. Net revenues Revenue from Contract with Customer, Excluding Assessed Tax Average assets under management Assets under Management, Average Balance Period end assets under management Assets under Management, Carrying Amount Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable interest entities [Member] Variable Interest Entity, Primary Beneficiary [Member] Statement [Line Items] Statement [Line Items] 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 Income Statement [Abstract] Administrative, distribution, and servicing fees [Member] Administrative, Distribution, And Servicing [Member] Administrative, Distribution, And Servicing [Member] Revenues Revenues, Net of Interest Expense [Abstract] Operating expenses Operating Expenses [Abstract] Compensation and related costs Labor and Related Expense Distribution and servicing costs Distribution Expenses Distribution Expenses Advertising and promotion Marketing and Advertising Expense Product-related costs Product-Related And Client Servicing Expenses Product-Related And Client Servicing Expenses Technology, occupancy, and facility costs Technology, Depreciation, Occupancy, And Facility Expenses Technology, Depreciation, Occupancy, And Facility Expenses General, administrative, and other Other General and Administrative Expense Nonrecurring net charge (recoveries) related to Dell appraisal rights matter Unusual or Infrequent Item, or Both, Net of Insurance Proceeds Total operating expenses Operating Expenses Net operating income Operating Income (Loss) Non-operating income Nonoperating Income (Expense) [Abstract] Net gains on investments Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Net gains (losses) on consolidated investment products Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Other income (loss) Other Nonoperating Income (Expense) Total non-operating income Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Provision for income taxes Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Less: net income (loss) 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 Earnings Per Share [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Statement of Stockholders' Equity [Abstract] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting standards update 2018-02, available for sale securities [Member] Accounting Standards Update 2018-02, Available for Sale Securities [Member] Accounting Standards Update 2018-02, Available for Sale Securities [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Retained earnings [Member] Retained Earnings, Unappropriated [Member] AOCI [Member] AOCI Attributable to Parent [Member] Cumulative effect of adopting new accounting guidance Cumulative Effect of New Accounting Principle in Period of Adoption Cash dividends declared per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Fair Value Disclosures [Abstract] Fair value measurements summary Fair Value, Assets Measured on Recurring Basis [Table Text Block] Other Disclosures [Abstract] Other Disclosures [Abstract] 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 Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] 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 Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock compensation plan [Member] Stock Compensation Plan [Member] 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. Options [Member] Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stockholder-approved 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 Disclosure of Compensation Related Costs, Share-based Payments [Abstract] STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] ASU 2014-09 [Member] Accounting Standards Update 2014-09 [Member] Adjustments For Reclassifications [Axis] Adjustments For Reclassifications [Axis] Adjustments For Reclassifications [Axis] Adjustments For Reclassifications [Domain] Adjustments For Reclassifications [Domain] [Domain] for Adjustments For Reclassifications [Axis] Change in Presentation [Member] Reclassifications Due To Presentation Change [Member] Reclassifications Due To Presentation Change [Member] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] As previously reported [Member] Previously Reported [Member] Restatement adjustment [Member] Restatement Adjustment [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Income Tax Disclosure [Abstract] Income tax provision related to the tax law changes Tax Cuts And Jobs Act Of 2017, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Income Tax Expense (Benefit) Provisional income tax related to the tax law changes 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 Reform [Table] Income Tax Reform [Table] Income Tax Reform [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State and local jurisdiction [Member] State and Local Jurisdiction [Member] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Comptroller of Maryland [Member] Comptroller Of Maryland [Member] Comptroller Of Maryland [Member] Income Tax Reform [Line Items] Income Tax Reform [Line Items] [Line Items] for Income Tax Reform [Table] Nonrecurring income tax charge due to Maryland state tax legislation Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Unremitted earnings of foreign subsidiaries Undistributed Earnings of Foreign Subsidiaries Tax refund receivables Income Taxes Receivable Net income taxes paid Income Taxes Paid, Net 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 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] 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 Unusual or Infrequent Item, or Both [Table] Unusual or Infrequent Item, or Both [Table] 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] Dell appraisal rights matter [Member] Dell appraisal rights matter [Member] Dell appraisal rights matter[Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Daiwa SB Investments Ltd [Member] Daiwa SB Investments Ltd [Member] Daiwa SB Investments Ltd [Member] Unusual or Infrequent Item, or Both [Line Items] Unusual or Infrequent Item, or Both [Line Items] Net revenues Net income Net income attributable to T. Rowe Price Group Basic earnings on common stock (in dollars per share) Diluted earnings per share (in dollars per share) Insurance proceeds Unusual or Infrequent Item, or Both, Insurance Proceeds Nonrecurring charge related to Dell appraisal rights matter Unusual or Infrequent Item, or Both, Loss, Gross Diluted earnings per share related to tax reform (in dollars per share) Tax Cuts And Jobs Act Of 2017, Effect On Earnings Per Share, Diluted Tax Cuts And Jobs Act Of 2017, Effect On Earnings Per Share, Diluted Ownership interest in investments (as percent) Investments, Ownership Interest Percentage Investments, Ownership Interest Percentage FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Schedule of impact of ASC 606 and other income statement reclassifications on condensed consolidated statements of income Schedule of New Accounting Pronouncements and Changes in Accounting Principles [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] Consolidated Sponsored Investment Portfolios [Abstract] Consolidated Sponsored Investment Portfolios [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [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] Equity securities [Member] Equity Securities [Member] Fixed income securities [Member] Fixed Income Investments [Member] Other investments [Member] Other than Securities Investment [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 Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [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 Investments Investments, Fair Value Disclosure Total Assets, Fair Value Disclosure Liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure 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). Property and equipment summary Property, Plant and Equipment [Table Text Block] 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 (benefits) Deferred Income Tax Expense (Benefit) Total Schedule of supplementary quarterly financial data Quarterly Financial Information [Table Text Block] Investments, Debt and Equity Securities [Abstract] Investment [Table] Investment [Table] Investment, Name [Axis] T. Rowe Price investment products [Member] Sponsored Investment Portfolios [Member] Sponsored Investment Portfolios [Member] T. Rowe Price investment products [Member] Sponsored Investment Portfolios Excluding Portfolios Designated As Economic Hedge Of Supplemental Savings Plan Liability [Member] Sponsored Investment Portfolios Excluding Portfolios Designated As Economic Hedge Of Supplemental Savings Plan Liability [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] Investment partnership and other investments [Member] Investment Partnership and Other Investments [Member] Investment Partnership and Other Investments [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 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. Currency translation adjustments [Member] Accumulated Foreign Currency Adjustment 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] Investment [Line Items] Investment [Line Items] Investment held at fair value Equity Securities, FV-NI Equity method investments Equity Method Investments U.S. Treasury note Debt Securities, Held-to-maturity Total Investments Equity method investment (ownership percentage) Equity Method Investment, Ownership Percentage Available for sale Available-for-sale Securities, Equity Securities Net unrealized gains on T. Rowe Price investments product recognized in nonoperating income Equity Securities, FV-NI, Unrealized Gain (Loss) 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 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 Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Shell Company Entity Shell Company 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 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] Maximum risk of loss related to investments in variable interest entities Schedule of Variable Interest Entities [Table Text Block] 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 Income [Table] Investment Income [Table] Net Investment Income [Line Items] Net Investment Income [Line Items] Dividend distribution Investment Income, Dividend Stockholders' Equity Note [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Net unrealized holding gains [Member] Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Total accumulated other comprehensive income [Member] Equity method investments [Member] Equity Method Investee [Member] Consolidated T. Rowe Price investment products - variable interest entities [Member] Accounting standards update 2016-01 [Member] Accounting Standards Update 2016-01 [Member] Accounting standards update 2018-02, currency translation adjustments [Member] Accounting Standards Update 2018-02, Currency Translation Adjustments [Member] Accounting Standards Update 2018-02, Currency Translation Adjustments [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Balances Stockholders' Equity Attributable to Parent 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. 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), Tax, Portion Attributable to Parent Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Balances 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] Land [Member] Land [Member] Leased land [Member] Leased Land [Member] Leased Land [Member] Compensation and related costs attributable to the development of computer software for internal use [Member] Software Development [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] 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 Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Voting interest entities [Member] Voting Interest Entities [Member] Voting Interest Entities [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable entities [Member] Reportable Legal Entities [Member] T.Rowe Price U.S. mutual funds [Member] 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] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value 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. 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 Compensation Deferred Income Tax Expense (Benefit), Related to Accrued 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 Asset impairments Deferred Income Tax Expense (Benefit), Related to Asset Impairments Deferred Income Tax Expense (Benefit), Related to Asset Impairments 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 (benefits) 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 Accounts receivable Accounts Receivable, Net Statement of Cash Flows [Abstract] Cash and cash equivalents Statement, Equity Components [Axis] Common stock [Member] Common Stock [Member] Additional capital in excess of par value [Member] Additional Paid-in Capital [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] Restricted shares [Member] Restricted Stock [Member] Restricted stock units [Member] Restricted Stock Units (RSUs) [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances (in shares) Shares, Outstanding Net income Other comprehensive income (loss), net of tax 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 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Shares issued upon option exercises Stock Issued During Period, Value, Stock Options Exercised Restricted shares withheld for taxes, net of shares issued (shares) Shares Paid for Tax Withholding for Share Based Compensation Shares withheld for taxes, net of shares issued Adjustments Related to Tax Withholding for Share-based Compensation Shares issued upon vesting of restricted stock units, net of shares withheld for taxes (shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross 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 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) Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balances attributable to redeemable non-controlling interests Cumulative effect of adopting new accounting guidance on redeemable noncontrolling interest 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. Net income attributable to redeemable non-controlling interests Other comprehensive loss, net of tax, attributable to redeemable 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 STOCKHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income Other comprehensive income (loss) Other Comprehensive Income (Loss), before Tax [Abstract] Currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax [Abstract] 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 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 Net unrealized holding gains (losses) on available-for-sale investments Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments and Tax Reclassification of (gains) 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 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), Securities, Available-for-sale, 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 (loss) 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 Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Net unrealized holding gains or losses [Member] 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 Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Non-operating income Provision for income taxes INCOME TAXES Income Tax Disclosure [Text Block] ASSETS Assets [Abstract] Accounts receivable and accrued revenue Assets of consolidated T. Rowe Price investment products ($1,392.6 million at December 31, 2018 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 ($22.7 million at December 31, 2018 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 238,069,000 shares at December 31, 2018 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 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 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] INVESTMENTS Investment [Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Consolidation eliminations [Member] Consolidation, Eliminations [Member] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Operating expenses reflected in net operating income Net investment income (loss) reflected in non-operating income Investment Income, Nonoperating Net income (loss) 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 BASIS OF PREPARATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] 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 NAV Per Share [Member] Fair Value Measured at Net Asset Value Per Share [Member] Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization of property and equipment Depreciation, Nonproduction 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 Net investments in T. Rowe Price investment products 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 operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of T. Rowe Price investment products Payments to Acquire Investments Dispositions T. Rowe Price investment products Proceeds from Sale, Maturity and Collection of Investments 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 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 provided by (used in) provided by 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 period, including $103.1 million at December 31, 2017 and $65.6 million at December 31, 2016 held by consolidated T. Rowe Price investment products 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 period, including $70.1 million at December 31, 2018, $103.1 million at December 31, 2017, and $65.6 million at December 31, 2016, held by consolidated T. Rowe Price investment products 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, Accrued Compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Accrued 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 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] New Accounting Guidance and 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] Investments held at fair value Marketable Securities, Policy [Policy Text Block] Equity method investments Equity Method Investments [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 from Contract with Customer [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] OTHER DISCLOSURES Other Disclosures [Text Block] Other Disclosures [Text Block] 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. 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] 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, 2017 (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Exercised (in shares) 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, 2018 (in shares) Exercisable at December 31, 2018 (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, 2017 (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, 2018 (in dollars per share) Weighted-average exercise price of options exercisable at December 31, 2018 (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 Stock-based compensation expense Allocated Share-based Compensation Expense 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 Unusual or Infrequent Items, or Both [Abstract] Nonrecurring charge (reversal) related to Dell appraisal rights matter Cash and Cash Equivalents [Abstract] CASH EQUIVALENTS Cash and Cash Equivalents Disclosure [Text Block] 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] 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) EARNINGS PER SHARE CALCULATIONS Earnings Per Share [Text Block] 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, 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, 2017 (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, 2018 (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, 2017 (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, 2018 (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 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. Estimated useful life Property, Plant and Equipment, Useful Life CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS Consolidated Sponsored Investment Portfolios [Text Block] Consolidated Sponsored Investment Portfolios [Text Block] First quarter 2019 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 2019 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 2019 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 2019 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 2019 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. 2020 through 2024 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 OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME Comprehensive Income (Loss) Note [Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] 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 Statutory U.S. federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Impact of nonrecurring charge relating to 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 Impact of nonrecurring charge related to Maryland state tax legislation Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, 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 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] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] 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) investing activities Net cash provided by (used in) financing activities FX impact on cash DELL APPRAISAL RIGHTS MATTER Unusual or Infrequent Items, or Both, Disclosure [Text Block] 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 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months Future minimum operating lease payments, due in 2020 Operating Leases, Future Minimum Payments, Due in Two Years Future minimum operating lease payments, due in 2021 Operating Leases, Future Minimum Payments, Due in Three Years Future minimum operating lease payments, due in 2022 Operating Leases, Future Minimum Payments, Due in Four Years Future minimum operating lease payments, due in 2023 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 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. 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] Restricted Cash and Cash Equivalents Items [Line Items] Restricted Cash and Cash Equivalents Items [Line Items] Dividends earned on money market mutual funds ASU 2016-01, adjustment for fair value [Member] Accounting Standards Update 2016-01, Adjustment For Fair Value Of Previous Cost Method Investments [Member] Accounting Standards Update 2016-01, Adjustment For Fair Value Of Previous Cost Method Investments [Member] ASU 2016-02 [Member] Accounting Standards Update 2016-02 [Member] ASU 2016-01 [Member] Accounting Standards Update 2016-01, Available-For-Sale Securities, Unrealized Gains (Losses) Reclassification [Member] Accounting Standards Update 2016-01, Available-For-Sale Securities, Unrealized Gains (Losses) Reclassification [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Forecast [Member] Scenario, Forecast [Member] Reclassification of accumulated other comprehensive income to retained earnings upon adoption of the new consolidation accounting guidance Increase in investment carrying value Investment Previously Accounted For As Cost Method, Increase (Decrease) Investment Previously Accounted For As Cost Method, Increase (Decrease) Increase in deferred taxes Increase (Decrease) In Deferred Tax Liabilities Increase (Decrease) In Deferred Tax Liabilities Reclassification adjustment of stranded tax benefits on currency translation adjustments upon adoption of new accounting guidance Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Foreign Currency Translation Adjustments, Tax Effect Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Foreign Currency Translation Adjustments, Tax Effect Right of use asset on operating lease Operating Lease, Right-of-Use Asset Operating lease liability Operating Lease, Liability Unsettled common stock repurchases liability Unsettled Common Stock Repurchases Liabilities Unsettled Common Stock Repurchases Liabilities Common shares authorized for future repurchase (shares) Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased Restricted stockholders' equity Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries