Consolidation - Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Noncontrolling interests	$ (131,525)	$ (112,482)	$ (115,513)	$ (90,687)	$ (87,115)	$ (63,845)
VOEs
Variable Interest Entity [Line Items]
Cash and cash equivalents	7,036		9,837
Investments	54,953		57,256
Other assets	13,962		1,989
Notes payable	0		0
Securities purchased payable and other liabilities	(20,534)		(2,566)
Noncontrolling interests	(16,975)		(24,707)
Net interests in CIP	38,442		41,809
CLOs
Variable Interest Entity [Line Items]
Cash and cash equivalents	121,934		82,295
Investments	2,154,956		2,217,055
Other assets	30,195		10,484
Notes payable	(2,132,012)		(2,190,445)
Securities purchased payable and other liabilities	(101,176)		(42,940)
Noncontrolling interests	(8,968)		(9,799)
Net interests in CIP	64,929		66,650
Other
Variable Interest Entity [Line Items]
Cash and cash equivalents	1,448		1,206
Investments	61,934		58,966
Other assets	889		957
Notes payable	0		0
Securities purchased payable and other liabilities	(634)		(323)
Noncontrolling interests	(5,611)		(3,354)
Net interests in CIP	$ 58,026		$ 57,452