CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS. (Statement of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 1,619.9	$ 229.5	$ 170.5
Net cash provided by (used in) investing activities	(875.5)	39.0	106.2
Net cash provided by (used in) financing activities	(1,239.5)	461.5	(176.4)
FX impact on cash	(15.4)	5.3	(2.1)
Net change in cash and cash equivalents during period	(510.5)	735.3	98.2
Cash and cash equivalents at beginning of period, including $103.1 million at December 31, 2017 and $65.6 million at December 31, 2016 held by consolidated T. Rowe Price investment products	2,005.8	1,270.5	1,172.3
Cash and cash equivalents at end of period, including $70.1 million at December 31, 2018, $103.1 million at December 31, 2017, and $65.6 million at December 31, 2016, held by consolidated T. Rowe Price investment products	1,495.3	2,005.8	1,270.5
Consolidation eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) financing activities	(84.9)	(130.1)	(277.9)
Consolidated T. Rowe Price investment products [Member] \| Reportable entities [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(549.1)	(1,315.3)	(1,166.6)
Net cash provided by (used in) investing activities	(23.8)	(64.2)	41.4
Net cash provided by (used in) financing activities	555.3	1,411.7	1,192.9
FX impact on cash	(15.4)	5.3	(2.1)
Net change in cash and cash equivalents during period	(33.0)	37.5	65.6
Cash and cash equivalents at beginning of period, including $103.1 million at December 31, 2017 and $65.6 million at December 31, 2016 held by consolidated T. Rowe Price investment products	103.1	65.6	0.0
Cash and cash equivalents at end of period, including $70.1 million at December 31, 2018, $103.1 million at December 31, 2017, and $65.6 million at December 31, 2016, held by consolidated T. Rowe Price investment products	70.1	103.1	65.6
Voting interest entities [Member] \| Reportable entities [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(43.9)	(33.0)	(80.1)
Net cash provided by (used in) investing activities	(0.8)	(9.0)	21.6
Net cash provided by (used in) financing activities	56.1	38.8	68.8
FX impact on cash	0.0	0.0	0.0
Net change in cash and cash equivalents during period	11.4	(3.2)	10.3
Cash and cash equivalents at beginning of period, including $103.1 million at December 31, 2017 and $65.6 million at December 31, 2016 held by consolidated T. Rowe Price investment products	7.1	10.3	0.0
Cash and cash equivalents at end of period, including $70.1 million at December 31, 2018, $103.1 million at December 31, 2017, and $65.6 million at December 31, 2016, held by consolidated T. Rowe Price investment products	18.5	7.1	10.3
Variable interest entities [Member] \| Reportable entities [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(505.2)	(1,282.3)	(1,086.5)
Net cash provided by (used in) investing activities	(23.0)	(55.2)	19.8
Net cash provided by (used in) financing activities	499.2	1,372.9	1,124.1
FX impact on cash	(15.4)	5.3	(2.1)
Net change in cash and cash equivalents during period	(44.4)	40.7	55.3
Cash and cash equivalents at beginning of period, including $103.1 million at December 31, 2017 and $65.6 million at December 31, 2016 held by consolidated T. Rowe Price investment products	96.0	55.3	0.0
Cash and cash equivalents at end of period, including $70.1 million at December 31, 2018, $103.1 million at December 31, 2017, and $65.6 million at December 31, 2016, held by consolidated T. Rowe Price investment products	$ 51.6	$ 96.0	$ 55.3

No definition available.

Name:	srt_CondensedCashFlowStatementsCaptionsLineItems
Namespace Prefix:	srt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash and Cash Equivalents, at Carrying Value, Including Consolidated Sponsored Investment Portfolios

+ References

No definition available.

+ Details

Name:	trow_CashandCashEquivalentsatCarryingValueIncludingConsolidatedSponsoredInvestmentPortfolios
Namespace Prefix:	trow_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 230
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906

+ Details

Name:	us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585

+ Details

Name:	us-gaap_NetCashProvidedByUsedInFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

+ References

+ Details

Name:	us-gaap_NetCashProvidedByUsedInInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3521-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_NetCashProvidedByUsedInOperatingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_ConsolidationItemsAxis=srt_ConsolidationEliminationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=trow_ConsolidatedInvestmentPortfoliosMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=srt_ReportableLegalEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=trow_VotingInterestEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: