Consolidation - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets
Cash equivalents	$ 171,633	$ 287,126
Total assets measured at fair value	263,027	374,279
Liabilities
Total liabilities measured at fair value	61,710	78,100
Level 1
Assets
Cash equivalents	171,633	287,126
Total assets measured at fair value	263,027	374,279
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	61,710	78,100
Fair Value, Measurements, Recurring | Consolidated Investment Products
Assets
Cash equivalents	201,987	249,003
Total assets measured at fair value	2,310,725	2,439,116
Liabilities
Notes payable	2,056,472	2,083,314
Short sales	484	414
Total liabilities measured at fair value	2,056,956	2,083,728
Fair Value, Measurements, Recurring | Debt investments | Consolidated Investment Products
Assets
Investments	2,083,417	2,161,571
Fair Value, Measurements, Recurring | Equity investments | Consolidated Investment Products
Assets
Investments	25,321	28,542
Fair Value, Measurements, Recurring | Level 1 | Consolidated Investment Products
Assets
Cash equivalents	201,987	249,003
Total assets measured at fair value	223,480	274,249
Liabilities
Notes payable	0	0
Short sales	484	414
Total liabilities measured at fair value	484	414
Fair Value, Measurements, Recurring | Level 1 | Debt investments | Consolidated Investment Products
Assets
Investments	227	243
Fair Value, Measurements, Recurring | Level 1 | Equity investments | Consolidated Investment Products
Assets
Investments	21,266	25,003
Fair Value, Measurements, Recurring | Level 2 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	2,076,587	2,121,286
Liabilities
Notes payable	2,056,472	2,083,314
Short sales	0	0
Total liabilities measured at fair value	2,056,472	2,083,314
Fair Value, Measurements, Recurring | Level 2 | Debt investments | Consolidated Investment Products
Assets
Investments	2,072,545	2,119,082
Fair Value, Measurements, Recurring | Level 2 | Equity investments | Consolidated Investment Products
Assets
Investments	4,042	2,204
Fair Value, Measurements, Recurring | Level 3 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	10,658	43,581
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	10,645	42,246
Fair Value, Measurements, Recurring | Level 3 | Equity investments | Consolidated Investment Products
Assets
Investments	$ 13	$ 1,335