Consolidation - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets
Cash equivalents	$ 92,458	$ 197,240
Total assets measured at fair value	196,698	307,226
Liabilities
Total liabilities measured at fair value	41,708	56,200
Level 1
Assets
Cash equivalents	92,458	197,240
Total assets measured at fair value	196,698	307,226
Liabilities
Total liabilities measured at fair value	0	0
Level 2
Assets
Cash equivalents	0	0
Total assets measured at fair value	0	0
Liabilities
Total liabilities measured at fair value	0	0
Level 3
Assets
Cash equivalents	0	0
Total assets measured at fair value	0	0
Liabilities
Total liabilities measured at fair value	41,708	56,200
Fair Value, Measurements, Recurring | Consolidated Investment Products
Assets
Cash equivalents	119,914	98,101
Total assets measured at fair value	2,201,139	2,180,814
Liabilities
Notes payable	1,922,051	1,922,243
Short sales	485	518
Total liabilities measured at fair value	1,922,536	1,922,761
Fair Value, Measurements, Recurring | Debt investments | Consolidated Investment Products
Assets
Investments	2,051,130	2,049,617
Fair Value, Measurements, Recurring | Equity investments | Consolidated Investment Products
Assets
Investments	30,095	33,096
Fair Value, Measurements, Recurring | Level 1 | Consolidated Investment Products
Assets
Cash equivalents	119,914	98,101
Total assets measured at fair value	149,383	130,984
Liabilities
Notes payable	0	0
Short sales	485	518
Total liabilities measured at fair value	485	518
Fair Value, Measurements, Recurring | Level 1 | Debt investments | Consolidated Investment Products
Assets
Investments	0	241
Fair Value, Measurements, Recurring | Level 1 | Equity investments | Consolidated Investment Products
Assets
Investments	29,469	32,642
Fair Value, Measurements, Recurring | Level 2 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	2,003,963	2,012,768
Liabilities
Notes payable	1,922,051	1,922,243
Short sales	0	0
Total liabilities measured at fair value	1,922,051	1,922,243
Fair Value, Measurements, Recurring | Level 2 | Debt investments | Consolidated Investment Products
Assets
Investments	2,003,579	2,012,760
Fair Value, Measurements, Recurring | Level 2 | Equity investments | Consolidated Investment Products
Assets
Investments	384	8
Fair Value, Measurements, Recurring | Level 3 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	47,793	37,062
Liabilities
Notes payable	0	0
Short sales	0	0
Total liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring | Level 3 | Debt investments | Consolidated Investment Products
Assets
Investments	47,551	36,616
Fair Value, Measurements, Recurring | Level 3 | Equity investments | Consolidated Investment Products
Assets
Investments	$ 242	$ 446