CONSOLIDATED T. ROWE PRICE INVESTMENT PRODUCTS. (Operating Results) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Income Statements, Captions [Line Items]
Operating expenses reflected in net operating income	$ (861.7)	$ (780.1)	$ (1,617.1)	$ (1,574.9)
Income before income taxes	968.8	739.6	1,175.7	1,474.9
Net income (loss) attributable to redeemable non-controlling interests	125.5	28.4	(51.0)	69.8
Consolidation eliminations
Condensed Income Statements, Captions [Line Items]
Operating expenses reflected in net operating income	(2.1)	(2.2)	(4.6)	(3.7)
Consolidated T. Rowe Price investment products
Condensed Income Statements, Captions [Line Items]
Income before income taxes	238.8	59.0	(95.2)	157.8
Net income (loss) attributable to T. Rowe Price Group	113.3	30.6	(44.2)	88.0
Net income (loss) attributable to redeemable non-controlling interests	125.5	28.4	(51.0)	69.8
Consolidated T. Rowe Price investment products | Reportable entities
Condensed Income Statements, Captions [Line Items]
Operating expenses reflected in net operating income	(3.6)	(3.8)	(7.3)	(6.9)
Net investment income (loss) reflected in non-operating income (loss)	242.4	62.8	(87.9)	164.7
Income before income taxes	238.8	59.0	(95.2)	157.8
Voting interest entities
Condensed Income Statements, Captions [Line Items]
Income before income taxes	16.1	10.7	(19.3)	18.4
Net income (loss) attributable to T. Rowe Price Group	12.9	5.2	(9.7)	13.9
Net income (loss) attributable to redeemable non-controlling interests	3.2	5.5	(9.6)	4.5
Voting interest entities | Reportable entities
Condensed Income Statements, Captions [Line Items]
Operating expenses reflected in net operating income	(0.3)	(0.7)	(0.5)	(1.0)
Net investment income (loss) reflected in non-operating income (loss)	16.4	11.4	(18.8)	19.4
Income before income taxes	16.1	10.7	(19.3)	18.4
Variable interest entities
Condensed Income Statements, Captions [Line Items]
Income before income taxes	222.7	48.3	(75.9)	139.4
Net income (loss) attributable to T. Rowe Price Group	100.4	25.4	(34.5)	74.1
Net income (loss) attributable to redeemable non-controlling interests	122.3	22.9	(41.4)	65.3
Variable interest entities | Reportable entities
Condensed Income Statements, Captions [Line Items]
Operating expenses reflected in net operating income	(3.3)	(3.1)	(6.8)	(5.9)
Net investment income (loss) reflected in non-operating income (loss)	226.0	51.4	(69.1)	145.3
Income before income taxes	$ 222.7	$ 48.3	$ (75.9)	$ 139.4