Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable and accrued revenue Accounts Receivable, Net Investments Investments Assets of consolidated T. Rowe Price investment products ($1,839.6 million at December 31, 2017, and $1,238.5 million at March 31, 2018, 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 T. Rowe Price investment products ($39.5 million at December 31, 2017, and $27.8 million at March 31, 2018, 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 Redeemable Noncontrolling Interest, Equity, Carrying Amount 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 245,111,000 shares at December 31, 2017, and 243,282,000 at March 31, 2018 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 Stockholders' Equity Attributable to Parent Total liabilities, redeemable non-controlling interests, and permanent stockholders’ equity Liabilities and Equity Stockholders' Equity Note [Abstract] OTHER COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME Comprehensive Income (Loss) Note [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] 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] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted stock units [Member] Restricted Stock Units (RSUs) [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 Cumulative effect adjustment upon adoption of new financial instruments and accumulated other comprehensive income guidance on January 1, 2018 Cumulative Effect of New Accounting Principle in Period of Adoption Reclassification adjustment of stranded tax benefits on currency translation adjustments upon adoption of new accumulated other comprehensive income guidance on January 1, 2018 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 Balances, As Adjusted Stockholders' Equity Attributable to Parent, Adjusted Balance Amount of stockholders' equity attributable to parent, after the cumulative effect adjustment of a new accounting principle applied in the period of adoption. Net income 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 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 Reclassification adjustment of stranded taxes on available-for-sale investments Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Available-For-Sale Investments, Tax Effect Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Available-For-Sale Investments, Tax Effect Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balances attributable to redeemable non-controlling interests 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 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 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 Net gains recognized on other investments Net Gains (Losses) Recognized on Investments Net Gains (Losses) Recognized on Investments Investments in U.S. mutual funds held as trading to economically hedge supplemental savings plan liability Proceeds from (Payments for) Trading Securities, Short-term Net change in trading securities held by consolidated T. Rowe Price investment products Increase (Decrease) In Trading Securities, Consolidated Sponsored Investment Portfolios Increase (Decrease) in Trading Securities, Consolidated Sponsored Investment Portfolios 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 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 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 T. Rowe Price investment products Effect of Exchange Rate on Cash and Cash Equivalents Net change in cash and cash equivalents during period Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of year Cash and Cash Equivalents, at Carrying Value, 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 Fair Value Disclosures [Abstract] FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Fair value measurements summary Fair Value, Assets Measured on Recurring Basis [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] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] T. Rowe Price money market mutual funds [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Sponsored U.S. Mutual Funds and Other Sponsored Investment Portfolios [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Consolidated T. Rowe Price investment products [Member] Consolidated Investment Portfolios [Member] Consolidated Investment Portfolios [Member] Voting interest entities [Member] Voting Interest Entities [Member] Voting Interest Entities [Member] Variable interest entities [Member] Variable Interest Entity, Primary Beneficiary [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable entities [Member] Reportable Legal Entities [Member] 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 Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Equity method investments [Member] Equity Method Investee [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] 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] Currency translation adjustments [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Total accumulated other comprehensive income (loss) [Member] Reclassification adjustment out of accumulated other comprehensive income Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Non-operating income Nonoperating Income (Expense) Provision for income taxes Income Tax Expense (Benefit) STOCKHOLDERS’ EQUITY Stockholders' Equity Note Disclosure [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Second quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Two Of Fiscal Year Unrecognized cost of unvested share-based compensation awards to be recognized in quarter two of the fiscal year. Third quarter 2018 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized Quarter Three Of Fiscal Year Unrecognized cost of unvested share-based compensation awards to be recognized in quarter three of the fiscal year. Fourth quarter 2018 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. 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 2023 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost To Be Recognized From Second Fiscal Year to Vesting Unrecognized cost of unvested share-based compensation awards to be recognized in the second fiscal year through vesting period. Total Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Organization, Consolidation and Presentation of Financial Statements [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2016-01, Available for sale securities, Unrealized gain reclassification [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] ASU 2016-01, Adjustment for fair value for previous cost method investments [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] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Cumulative effect adjustment upon adoption of new accounting guidance Available-for-sale investments Available-for-sale Securities, Equity Securities 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 Information about Receivables, Revenues, and Services [Abstract] Information about Receivables, Revenues, and Services 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] T. Rowe Price investment products [Member] Sponsored Investment Portfolios [Member] Sponsored Investment Portfolios [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 Net revenues Investment Advisory, Management and Administrative Fees Accounts receivable 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). Statement of Comprehensive Income [Abstract] 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 gains recognized in non-operating income upon dispositions, determined using average cost Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of 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 T. Rowe Price investment products - variable interest entities Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Reclassification gain recognized in non-operating 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 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 Income Statement [Abstract] Revenues Revenues, Net of Interest Expense [Abstract] Investment advisory fees Investment Advisory Fees Administrative, distribution, and servicing fees Administrative Services Revenue And Distribution Fees Administrative Services Revenue And Distribution Fees Net revenues Operating expenses Operating Expenses [Abstract] Compensation and related costs Labor and Related Expense Distribution and servicing 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 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 gains on investments Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Other Than Consolidated Sponsored Investment Portfolios Net gains on consolidated investment portfolios Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Investment Income, Nonoperating, Consolidated Sponsored Investment Portfolios Other income Other Nonoperating Income (Expense) Total non-operating income Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Provision for income taxes Net income Less: net income attributable to redeemable non-controlling interests Net income 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 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 Supplementary consolidating cash flow statement Condensed Cash Flow Statement [Table Text Block] Assets of consolidated T. Rowe Price investment products Liabilities of consolidated T. Rowe Price investment products 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 Investment [Table] Investment [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] T. Rowe Price investment products 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] Investment partnerships 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 and other investments [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 noncontrolling interest [Member] Redeemable Noncontrolling Interest [Member] The line item on the balance sheet representing the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity. Investment [Line Items] Investment [Line Items] Investments held at fair value Equity Securities, FV-NI Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Cost method investments Cost Method Investments Equity method investments Equity Method Investments U.S. Treasury note Held-to-maturity Securities Total Equity method investment (ownership percentage) Equity Method Investment, Ownership Percentage Net unrealized losses on T. Rowe Price investments product recognized in nonoperating income Equity Securities, FV-NI, Unrealized Gain (Loss) Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Net increase (decrease) in assets, liabilities, and redeemable noncontrolling interest Deconsolidation Value2 Represents the carrying value of the assets (liabilities or redeemable noncontrolling interest) deconsolidated during the period as valued on the date that the parent no longer had a controlling financial interest in the subsidiary. Gains (losses) recognized upon deconsolidation 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] 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 THE COMPANY AND BASIS OF PREPARATION Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Unusual or Infrequent Items, or Both [Abstract] DELL APPRAISAL RIGHTS MATTER Unusual or Infrequent Items, or Both, Disclosure [Text Block] 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. U.S. mutual funds [Member] Sponsored Mutual Funds In U S [Member] Sponsored mutual funds in the U.S. Subadvised and separately managed accounts and other investment products [Member] Other Portfolios [Member] Other portfolios Other [Member] Other Clients [Member] Other Clients [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Equity and blended asset [Member] Stock And Blended Asset [Member] Stock and blended asset [Member] Fixed income 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. Administrative fees Administrative Services Revenue Distribution and servicing fees Distribution Fees Average assets under management Assets under Management, Average Balance Period end assets under management Assets under Management, Carrying Amount Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Net unrealized holding gains [Member] Consolidated T. Rowe Price investment products - variable interest entities [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] 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 income taxes Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Other comprehensive income (loss) Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] 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 Total Assets, Fair Value Disclosure Liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Restricted shares [Member] Restricted Stock [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Time-based [Member] Share-based Compensation Award, Tranche One [Member] Performance-based [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Nonvested at December 31, 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 March 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 March 31, 2018 (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 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 (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) 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 and cash equivalents Unusual or Infrequent Item [Table] Unusual or Infrequent Item, or Both [Table] Gain Contingencies, Nature [Axis] Gain Contingencies, Nature [Axis] Gain Contingency, Nature [Domain] Gain Contingency, Nature [Domain] Dell appraisal rights matter [Member] Dell appraisal rights matter [Member] Dell appraisal rights matter[Member] Unusual or Infrequent Item [Axis] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item [Domain] Unusual or Infrequent Item, or Both [Domain] 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 Insurance proceeds Unusual or Infrequent Item, or Both, Insurance Proceeds Price offered per share in Dell merger (in dollars per share) Price Offered, Per Share Price Offered, Per Share Unrecorded gain contingency Gain Contingency, Unrecorded Amount New Accounting Guidance and Newly Issued But Not Yet Adopted Accounting Guidance New Accounting Pronouncements, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Comprehensive Income Comprehensive Income, Policy [Policy Text Block] EARNINGS PER SHARE CALCULATIONS Earnings Per Share [Text Block] SUPPLEMENTARY CONSOLIDATING CASH FLOW STATEMENT Condensed Financial Statements [Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] As previously reported [Member] Scenario, Previously Reported [Member] Adjustment [Member] Restatement Adjustment [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] Impact of ASC 606 [Member] Accounting Standards Update 2014-09 [Member] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS Consolidated Sponsored Investment Portfolios [Text Block] Consolidated Sponsored Investment Portfolios [Text Block] 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 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 T. Rowe Price investment products [Member] Consolidation eliminations [Member] Consolidation, Eliminations [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Investments in U.S. mutual funds held as trading to economically hedge supplemental savings plan liability Net cash provided by (used in) investing activities Net cash provided by (used in) financing activities INVESTMENTS Investment [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. 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 Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products Cash and cash equivalents at beginning of year Cash and cash equivalents at end of period 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) 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 March 31, 2018 (in shares) Exercisable at March 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 March 31, 2018 (in dollars per share) Weighted-average exercise price of options exercisable at March 31, 2018 (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price 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 Fair value measured at NAV [Member] Fair Value Measured At Net Asset Value Per Share [Member] Fair Value Measured At Net Asset Value Per Share [Member] T. Rowe Price investment products 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] 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 STOCK-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] 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 Accounts payable and accrued expenses Unsettled Common Stock Repurchases Liabilities Unsettled Common Stock Repurchases Liabilities