Consolidation - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets
Cash equivalents	$ 167,311	$ 307,277
Total assets measured at fair value	268,433	400,933
Liabilities
Total liabilities measured at fair value	70,080	88,400
Level 1
Assets
Cash equivalents	167,311	307,277
Total assets measured at fair value	268,433	400,933
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	70,080	88,400
Fair Value, Measurements, Recurring | Consolidated Investment Products
Assets
Cash equivalents	108,396	205,192
Total assets measured at fair value	2,227,004	2,345,430
Liabilities
Notes payable	1,978,420	2,033,617
Short sales	459	515
Total liabilities measured at fair value	1,978,879	2,034,132
Fair Value, Measurements, Recurring | Debt investments | Consolidated Investment Products
Assets
Investments	2,094,540	2,110,704
Fair Value, Measurements, Recurring | Equity investments | Consolidated Investment Products
Assets
Investments	24,068	29,534
Fair Value, Measurements, Recurring | Level 1 | Consolidated Investment Products
Assets
Cash equivalents	108,396	205,192
Total assets measured at fair value	126,579	231,576
Liabilities
Notes payable	0	0
Short sales	459	515
Total liabilities measured at fair value	459	515
Fair Value, Measurements, Recurring | Level 1 | Debt investments | Consolidated Investment Products
Assets
Investments	122	273
Fair Value, Measurements, Recurring | Level 1 | Equity investments | Consolidated Investment Products
Assets
Investments	18,061	26,111
Fair Value, Measurements, Recurring | Level 2 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	2,058,112	2,110,697
Liabilities
Notes payable	1,978,420	2,033,617
Short sales	0	0
Total liabilities measured at fair value	1,978,420	2,033,617
Fair Value, Measurements, Recurring | Level 2 | Debt investments | Consolidated Investment Products
Assets
Investments	2,053,468	2,107,736
Fair Value, Measurements, Recurring | Level 2 | Equity investments | Consolidated Investment Products
Assets
Investments	4,644	2,961
Fair Value, Measurements, Recurring | Level 3 | Consolidated Investment Products
Assets
Cash equivalents	0	0
Total assets measured at fair value	42,313	3,157
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	40,950	2,695
Fair Value, Measurements, Recurring | Level 3 | Equity investments | Consolidated Investment Products
Assets
Investments	$ 1,363	$ 462