Consolidation - Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total cash and cash equivalents	$ 179,039	$ 82,687	$ 247,670	$ 97,384
Noncontrolling interests	(57,336)	(37,266)	$ (27,145)	$ (73,864)
VOEs
Variable Interest Entity [Line Items]
Total cash and cash equivalents	909	1,859
Investments	31,559	99,247
All other assets	1,092	2,211
Notes payable	0	0
Securities purchased payable and other liabilities	(1,667)	(2,310)
Noncontrolling interests	(3,632)	(12,505)
The Company’s net interests in consolidated investment vehicles	28,261	88,502
CLOs
Variable Interest Entity [Line Items]
Total cash and cash equivalents	48,135	14,449
Investments	1,263,265	346,967
All other assets	24,186	5,888
Notes payable	(1,096,434)	(328,761)
Securities purchased payable and other liabilities	(137,177)	(12,534)
Noncontrolling interests	(15,731)	0
The Company’s net interests in consolidated investment vehicles	86,244	26,009
Other
Variable Interest Entity [Line Items]
Total cash and cash equivalents	3,278	2,775
Investments	59,565	42,828
All other assets	2,508	1,059
Notes payable	0	0
Securities purchased payable and other liabilities	(4,214)	(1,799)
Noncontrolling interests	(53,704)	(24,761)
The Company’s net interests in consolidated investment vehicles	$ 7,433	$ 20,102