CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS. (Statement of Cash Flows) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 1,916.9	$ 1,500.7
Net cash used in investing activities	(53.1)	(76.7)
Net cash provided by in financing activities	(1,419.3)	(623.0)
Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products	3.4	(2.2)
Net change in cash and cash equivalents during period	447.9	798.8
Cash and cash equivalents at beginning of period	1,858.3	1,495.3
Cash and cash equivalents at ending of period	2,306.2	2,294.1
Consolidation eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by in financing activities	95.2	157.7
Consolidated T. Rowe Price investment products
Condensed Cash Flow Statements, Captions [Line Items]
Cash and cash equivalents at beginning of period	76.5	70.1
Cash and cash equivalents at ending of period	78.0	80.9
Consolidated T. Rowe Price investment products | Reportable entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(346.7)	(523.5)
Net cash used in investing activities	(49.1)	(8.3)
Net cash provided by in financing activities	393.9	544.8
Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products	3.4	(2.2)
Net change in cash and cash equivalents during period	1.5	10.8
Cash and cash equivalents at beginning of period	76.5	70.1
Cash and cash equivalents at ending of period	78.0	80.9
Voting interest entities | Reportable entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(105.7)	(15.1)
Net cash used in investing activities	(23.4)	(7.4)
Net cash provided by in financing activities	124.4	15.5
Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products	0.0	0.0
Net change in cash and cash equivalents during period	(4.7)	(7.0)
Cash and cash equivalents at beginning of period	9.9	18.5
Cash and cash equivalents at ending of period	5.2	11.5
Variable interest entities | Reportable entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(241.0)	(508.4)
Net cash used in investing activities	(25.7)	(0.9)
Net cash provided by in financing activities	269.5	529.3
Effect of exchange rate changes on cash and cash equivalents of consolidated T. Rowe Price investment products	3.4	(2.2)
Net change in cash and cash equivalents during period	6.2	17.8
Cash and cash equivalents at beginning of period	66.6	51.6
Cash and cash equivalents at ending of period	$ 72.8	$ 69.4