Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted shares [Member] Restricted Stock [Member] Restricted stock units [Member] Restricted Stock Units (RSUs) [Member] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] 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] AOCI Attributable to Parent [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances (in shares) Shares, Outstanding Balances Stockholders' Equity Attributable to Parent Net income Net Income (Loss) Attributable to Parent 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 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 Redeemable Noncontrolling Interest, Equity, Carrying Amount Net income attributable to redeemable non-controlling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Other comprehensive income (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 sponsored investment portfolios 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 sponsored investment portfolios Noncontrolling Interest, Decrease from Deconsolidation Ending balances attributable to redeemable non-controlling interests Information about Receivables, Revenues, and Services [Abstract] Information about Receivables, Revenues, and Services Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Sponsored U.S. mutual funds and other sponsored investment portfolios [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Receivables from sponsored mutual funds Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts receivable for advisory fees and advisory-related administrative services Accounts Receivable, Net Investments, Debt and Equity Securities [Abstract] 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 Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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] Depreciation and amortization of property and equipment Depreciation, Nonproduction Stock-based compensation expense Share-based Compensation Realized gains on dispositions of available-for-sale sponsored investment portfolios Available-for-sale Securities, Gross Realized Gains Gains recognized upon transfer of an available-for-sale sponsored investment portfolio to sponsored investment portfolios 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 sponsored investment portfolios 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 sponsored investment portfolios Increase (Decrease) In Trading Securities, Consolidated Sponsored Investment Portfolios Increase (Decrease) in Trading Securities, Consolidated Sponsored Investment Portfolios Other changes in assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by (used in) 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 available-for-sale sponsored investment portfolios Payments to Acquire Available-for-sale Securities, Equity Dispositions of available-for-sale sponsored investment portfolios Proceeds from Sale of Available-for-sale Securities, Equity Net cash of sponsored investment portfolios 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 stockholders of T. Rowe Price Group Payments of Dividends Net subscriptions received from redeemable non-controlling interest holders Proceeds from (Payments to) Noncontrolling Interests 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 sponsored investment portfolios 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, 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 Statement of Comprehensive Income [Abstract] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Variable interest entities [Member] Variable Interest Entity, Primary Beneficiary [Member] Equity method investments [Member] Equity Method Investee [Member] Other comprehensive income (loss) Other Comprehensive Income (Loss), before Tax [Abstract] Net unrealized holding gains on available-for-sale investments Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments and Tax Reclassification adjustments recognized 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 Reclassification adjustments recognized in non-operating income: 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 net unrealized holding gains (losses) recognized in other comprehensive income Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax Consolidated sponsored investment portfolios - variable interest entities Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Reclassification gain recognized in non-operating investment income upon deconsolidation of sponsored fund subsidiary Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other comprehensive income (loss) before income taxes Other Comprehensive Income (Loss), before Tax Net deferred tax benefits (income taxes) 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 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. 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 Fair Value Disclosures [Abstract] Fair value measurements summary Fair Value, Assets Measured on Recurring Basis [Table Text Block] Unusual or Infrequent Items, or Both [Abstract] DELL APPRAISAL RIGHTS MATTER Unusual or Infrequent Items, or Both, Disclosure [Text Block] 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] 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] 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 sponsored investment portfolios [Member] Consolidated Investment Portfolios [Member] Consolidated Investment Portfolios [Member] 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] 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 [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] 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 Trading investments Trading Securities Total Assets, Fair Value Disclosure Liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Stockholders' Equity Note [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Net unrealized holding gains or losses [Member] Accumulated Net Investment Gain (Loss) 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 Currency translation adjustments [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Total accumulated other comprehensive income (loss) [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Net deferred tax benefits (income taxes) on other comprehensive income (loss) 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 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. Sponsored 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 Administrative Services Revenue Distribution and servicing fees Distribution Fees 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 September 30, 2017 (in shares) Exercisable at September 30, 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 September 30, 2017 (in dollars per share) Weighted-average exercise price of options exercisable at September 30, 2017 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Net unrealized holding gains [Member] Consolidated sponsored investment portfolios - variable interest entities [Member] AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Other comprehensive income 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) Organization, Consolidation and Presentation of Financial Statements [Abstract] SUPPLEMENTARY CONSOLIDATING CASH FLOW STATEMENT Condensed Financial Statements [Text Block] EARNINGS PER SHARE CALCULATIONS Earnings Per Share [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. Other investment portfolios [Member] Other Portfolios [Member] Other portfolios Other sponsored investment portfolios [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] 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] Revenues from advisory services Investment Advisory Fees Average assets under management Assets under Management, Average Balance Period end assets under management Assets under Management, Carrying Amount Impact of the components of other comprehensive income (loss) 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] Condensed Cash Flow Statement [Table] Condensed Cash Flow 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] 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) investing activities Net cash provided by (used in) financing activities Effect of exchange rate changes on cash and cash equivalents of consolidated sponsored investment portfolios Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Supplementary consolidating cash flow statement Condensed Cash Flow Statement [Table Text Block] Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies 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 Available-for-sale Securities, Equity Securities 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 sponsored investment portfolios 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] Unusual or Infrequent Item [Table] Unusual or Infrequent Item, or Both [Table] Unusual or Infrequent Item [Axis] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item [Domain] Unusual or Infrequent Item, or Both [Domain] Dell appraisal rights matter [Member] Dell appraisal rights matter [Member] Dell appraisal rights matter[Member] Unusual or Infrequent Item [Line Items] Unusual or Infrequent Item, or Both [Line Items] Nonrecurring charge, net of insurance recovery, 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 The price per share offered in a merger by the buyer, that was determined by a court to be too low during the period. 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 Insurance proceeds, received Proceeds from Insurance Settlement, Operating Activities Investment [Table] Investment [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Sponsored investment portfolios [Member] Sponsored Investment Portfolios [Member] Sponsored Investment Portfolios [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] 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 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 interests [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. 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] Available-for-sale sponsored investment portfolios Equity method investments Equity Method Investments Cost method investments Cost Method Investments U.S. Treasury note Held-to-maturity Securities Total Investments 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. Gain recognized upon deconsolidation Nonoperating Income (Expense) Sponsored investment portfolios held as trading Income Statement [Abstract] Revenues Revenues, Net of Interest Expense [Abstract] Investment advisory fees Administrative fees Distribution and servicing fees Net revenues Investment Advisory, Management and Administrative Fees 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 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 Operating Expenses Net operating income Operating Income (Loss) Non-operating income Nonoperating Income (Expense) [Abstract] Net investment income on investments Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Net investment income on consolidated sponsored investment portfolios 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 Income Tax Expense (Benefit) Net income Less: net income attributable to redeemable non-controlling interests Net income attributable to T. Rowe Price Group 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 Dividends declared per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Accounts receivable and accrued revenue Investments Assets of consolidated sponsored investment portfolios ($1,446.1 million at December 31, 2016, and $1,845.5 million at September 30, 2017, related to variable interest entities) Variable Interest Entity, Consolidated, Carrying Amount, Assets Property and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Other assets Other Assets Total assets Assets LIABILITIES Liabilities [Abstract] Accounts payable and accrued expenses Accounts Payable and Other Accrued Liabilities Liabilities of consolidated sponsored investment portfolios ($56.8 million at December 31, 2016, and $43.3 million at September 30, 2017, related to variable interest entities) Variable Interest Entity, Consolidated, Carrying Amount, Liabilities 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 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 242,214,000 at September 30, 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 Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification adjustment out of accumulated other comprehensive income Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Non-operating income Provision for income taxes THE COMPANY AND BASIS OF PREPARATION Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Liabilities Net assets Net Assets 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. Attributable to redeemable non-controlling interests Net income attributable to T. Rowe Price Group Less: net income allocated to outstanding restricted stock and stock unit holders Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Less: net income allocated to outstanding restricted stock and stock unit holders 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 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] Attributable to consolidated sponsored investment portfolios [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Net cash provided by (used in) investing activities Net cash provided by (used in) financing activities 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] Fund holdings with temporary unrealized 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 Fund holdings with temporary unrealized losses longer than 12 months (number of securities) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Fund holdings with temporary 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 on fund 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 on fund holdings that were in a continuous loss for longer than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Unrealized holding losses on fund 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] Unrealized holding losses for less than 12 months at period end are attributable to fund holdings with an aggregate fair value of Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Unrealized holding losses for longer than 12 months at period end are attributable to fund holdings with an aggregate fair value of Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Unrealized holding losses at period end are attributable to fund holdings with an aggregate fair value of Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Cash and cash equivalents INVESTMENTS Investment [Text Block] OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME Comprehensive Income (Loss) Note [Text Block] CONSOLIDATED SPONSORED INVESTMENT PORTFOLIOS Consolidated Sponsored Investment Portfolios [Text Block] Consolidated Sponsored Investment Portfolios [Text Block] Fourth quarter 2017 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Four Of Fiscal Year Unrecognized cost of unvested share-based compensation awards to be recognized in quarter four of the fiscal year. 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 2022 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 Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Operating expenses Non-operating investment 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 Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] 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 September 30, 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 September 30, 2017 (in dollars per share) 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 STOCKHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Assets of consolidated sponsored investment portfolios Liabilities of consolidated sponsored investment portfolios 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 Net assets of consolidated sponsored 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 sponsored 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 sponsored 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 sponsored 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). Stockholders' Equity Note [Table] Stockholders' Equity Note [Table] Stockholders' Equity Note [Table] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Regular cash dividend [Member] Ordinary Dividend [Member] Ordinary Dividend [Member] Stockholders' Equity Note [Line Items] Stockholders' Equity Note [Line Items] [Line Items] for Stockholders' Equity Note [Table] Cash dividends declared per share 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 Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding (shares) Entity Common Stock, Shares Outstanding Entity Central Index Key Entity Central Index Key Amendment Flag Amendment Flag