Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net income	$ 106.6	$ 86.8	$ 67.1
Adjustments to reconcile net income to net cash flows from operating activities:
Loss on extinguishment of debt	1.4	0.0	0.0
Deferred income taxes	1.5	(10.2)	(6.0)
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	(2.4)	55.8	68.3
Cash flows from investing activities of consolidated Funds:
Net cash flows from investing activities	15.7	(50.1)	(43.9)
Cash flows from financing activities of consolidated Funds:
Net cash flows from financing activities	12.1	(54.4)	1.8
Effect of foreign exchange rate changes on cash and cash equivalents	0.5	(0.4)	0.2
Net increase (decrease) in cash and cash equivalents	25.9	(49.1)	26.4
Cash and cash equivalents at beginning of period (including restricted cash)	98.5	147.6	121.2
Cash and cash equivalents at end of period (including restricted cash)	124.4	98.5	147.6
Cash and cash equivalents
Cash and cash equivalents at end of period (including restricted cash)	124.4	98.5	147.6
Supplemental disclosure of cash flow information:
Income taxes paid	34.2	48.5	37.8
Supplemental disclosure of non-cash investing and financing transactions:
Excise tax on repurchases of common stock	0.4	0.7	0.0
Payable for repurchases of common stock	0.0	0.0	(1.8)
Consolidated Entity Excluding Consolidated Funds
Cash flows from operating activities:
Net income	106.6	86.8	67.1
Less: Net income attributable to redeemable non-controlling interests in consolidated Funds	(26.6)	(1.8)	(1.3)
Adjustments to reconcile net income to net cash flows from operating activities:
Loss on extinguishment of debt	1.4	0.0	0.0
Depreciation and amortization	16.6	18.5	17.3
Amortization of debt-related costs	7.2	4.4	4.1
Amortization and revaluation of non-cash compensation awards	53.8	30.5	7.4
Deferred income taxes	1.5	(10.2)	(6.0)
(Gains) on other investments	(13.4)	(12.5)	(5.6)
Changes in operating assets and liabilities:
(Increase) in investment advisory fees receivable	(13.8)	(21.3)	(20.9)
Decrease in other receivables, prepayments, deposits and other assets	0.9	0.6	0.2
Increase (decrease) in accrued incentive compensation, operating lease liabilities and other liabilities	(5.1)	15.1	10.2
Increase (decrease) in accounts payable, accrued expenses and accrued income taxes	0.7	(1.2)	5.2
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:
(Gains) on other investments	(13.4)	(12.5)	(5.6)
Total net cash flows from operating activities	129.8	108.9	77.7
Cash flows from investing activities:
Additions of fixed assets	(11.9)	(9.9)	(13.8)
Purchase of investment securities	(17.9)	(47.7)	(25.8)
Sale of investment securities	35.1	7.5	8.2
Cash flows from financing activities:
Proceeds from third party borrowings and revolving credit facility	337.0	139.0	113.5
Repayment of third party borrowings and revolving credit facility	(413.1)	(139.0)	(113.5)
Payment of debt issuance costs	(2.6)	(0.7)	0.0
Proceeds from stock issuance	0.0	0.1	0.0
Payment to OM plc for co-investment redemptions	0.0	(0.2)	(0.4)
Repurchases of common stock	(48.8)	(96.7)	(3.3)
Withholding tax payments related to stock option exercise and restricted stock vesting	(0.2)	(11.4)	(2.4)
Cash and cash equivalents
Cash and cash equivalents	101.2	94.8	146.8
Supplemental disclosure of cash flow information:
Interest paid (excluding consolidated Funds)	20.0	15.0	15.5
Consolidated Entity Excluding Consolidated Funds | Nonrelated Party
Cash flows from financing activities:
Dividends paid to stockholders	(1.0)	(0.9)	(1.4)
Consolidated Entity Excluding Consolidated Funds | Related Party
Cash flows from financing activities:
Dividends paid to stockholders	(0.5)	(0.6)	(0.6)
Consolidated Funds
Cash flows from operating activities:
Less: Net income attributable to redeemable non-controlling interests in consolidated Funds	26.6	1.8	1.3
Adjustments to reconcile net income to net cash flows from operating activities:
(Gains) on other investments	(21.0)	0.4	(1.1)
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:
(Gains) on other investments	(21.0)	0.4	(1.1)
Purchase of investments	(642.9)	(167.1)	(19.7)
Sale of investments	447.9	112.3	13.6
(Increase) decrease in receivables and other assets	116.6	(0.9)	(3.5)
Increase (decrease) in accounts payable and other liabilities	(59.4)	0.4	0.0
Total net cash flows from operating activities	(132.2)	(53.1)	(9.4)
Cash flows from investing activities of consolidated Funds:
Net consolidation (deconsolidation) of Funds	10.4	0.0	(12.5)
Cash flows from financing activities of consolidated Funds:
Redeemable non-controlling interest capital raised	146.3	56.0	9.9
Redeemable non-controlling interest capital redeemed	(5.0)	0.0	0.0
Cash and cash equivalents
Cash and cash equivalents of consolidated Funds, restricted	$ 23.2	$ 3.7	$ 0.8