Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Cash flows from operating activities:
Net income	$ 42.9	$ 27.2
Adjustments to reconcile net income (loss) attributable to redeemable non-controlling interests of consolidated Funds to net cash flows from operating activities of consolidated Funds:
Total net cash flows from operating activities	12.8	5.3
Cash flows from investing activities:
Net cash flows from investing activities	9.1	(18.8)
Cash flows from financing activities of consolidated Funds:
Net cash flows from financing activities	(26.9)	(60.6)
Effect of foreign exchange rate changes on cash and cash equivalents	0.4	(0.1)
Net decrease in cash and cash equivalents	(4.6)	(74.2)
Cash and cash equivalents at beginning of period	98.5	147.6
Cash and cash equivalents at end of period	93.9	73.4
Cash and cash equivalents at end of period
Cash and cash equivalents	93.9	73.4
Supplemental disclosure of cash flow information:
Income taxes paid	22.4	23.3
Supplemental disclosure of non-cash financing transactions:
Excise tax on repurchase of common stock	0.4	0.8
Consolidated Entity Excluding Consolidated Funds
Cash flows from operating activities:
Net income	42.9	27.2
Less: Net income attributable to redeemable non-controlling interests in consolidated Funds	(12.7)	(1.6)
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	8.4	9.6
Amortization of debt-related costs	2.3	2.2
Amortization and revaluation of non-cash compensation awards	22.0	14.1
Deferred income taxes	(4.9)	(5.6)
(Gains) on other investments	(6.7)	(6.3)
Changes in operating assets and liabilities:
Decrease in investment advisory fees receivable	40.5	31.1
(Increase) in other receivables, prepayments, deposits and other assets	(6.7)	(7.2)
(Decrease) in accrued incentive compensation, operating lease liabilities and other liabilities	(67.7)	(46.6)
(Decrease) in accounts payable, accrued expenses and accrued income taxes	(6.7)	(11.5)
Adjustments to reconcile net income (loss) attributable to redeemable non-controlling interests of consolidated Funds to net cash flows from operating activities of consolidated Funds:
Total net cash flows from operating activities	10.7	5.4
Cash flows from investing activities:
Additions of fixed assets	(5.4)	(5.0)
Purchase of investment securities	(2.6)	(17.4)
Sale of investment securities	17.1	3.6
Cash flows from financing activities:
Proceeds from revolving credit facility	125.0	124.0
Repayment of revolving credit facility	(105.0)	(88.0)
Payment to OM plc for co-investment redemptions	0.0	(0.2)
Repurchase of common stock	(43.8)	(94.9)
Withholding tax payments related to stock option exercise and restricted stock vesting	(0.2)	(1.8)
Cash and cash equivalents at end of period
Cash and cash equivalents	90.2	71.6
Supplemental disclosure of cash flow information:
Interest paid (excluding consolidated Funds)	7.7	8.2
Consolidated Entity Excluding Consolidated Funds | Nonrelated Party
Cash flows from financing activities:
Dividends paid to stockholders	(0.5)	(0.5)
Consolidated Entity Excluding Consolidated Funds | Related Party
Cash flows from financing activities:
Dividends paid to stockholders	(0.3)	(0.3)
Consolidated Funds
Cash flows from operating activities:
Less: Net income attributable to redeemable non-controlling interests in consolidated Funds	12.7	1.6
Adjustments to reconcile net income to net cash flows from operating activities:
(Gains) on other investments	(10.5)	(0.7)
Adjustments to reconcile net income (loss) attributable to redeemable non-controlling interests of consolidated Funds to net cash flows from operating activities of consolidated Funds:
Purchase of investments	(135.4)	(37.0)
Sale of investments	139.7	35.5
(Increase) decrease in receivables and other assets	(5.1)	0.3
Increase in accounts payable and other liabilities	0.7	0.2
Total net cash flows from operating activities	2.1	(0.1)
Cash flows from financing activities of consolidated Funds:
Redeemable non-controlling interest capital raised	(2.1)	1.1
Cash and cash equivalents at end of period
Cash and cash equivalents	$ 3.7	$ 1.8