FAIR VALUE MEASUREMENTS - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents held in money market funds	$ 3,049.0	$ 2,309.8
Other investments	0.3	0.1
Investments in affiliated collateralized loan obligations	0.0	0.0
Total	5,014.9	3,770.9
Level 1 | Discretionary investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	463.7	258.8
Level 1 | Redeemable seed capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	258.6	209.4
Level 1 | Investments used to hedge the deferred compensation liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	1,243.3	992.8
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents held in money market funds	0.0	0.0
Other investments	0.0	0.0
Investments in affiliated collateralized loan obligations	3.2	6.3
Total	60.7	59.7
Level 2 | Discretionary investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	0.0	0.0
Level 2 | Redeemable seed capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	57.5	53.4
Level 2 | Investments used to hedge the deferred compensation liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
T. Rowe Price investment products	$ 0.0	$ 0.0