Consolidation - Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 201,705	$ 132,150
Noncontrolling interests	(57,481)	(4,178)	$ (37,266)	$ (73,864)
VOEs
Variable Interest Entity [Line Items]
Cash and cash equivalents	1,029	820
Investments	12,923	34,623
Other assets	228	767
Notes payable	0	0
Securities purchased payable and other liabilities	(823)	(1,319)
Noncontrolling interests	(2,348)	(4,178)
The Company’s net interests in consolidated investment products	11,009	30,713
CLOs
Variable Interest Entity [Line Items]
Cash and cash equivalents	51,363	82,823
Investments	1,709,266	1,555,879
Other assets	30,426	32,671
Notes payable	(1,620,260)	(1,457,435)
Securities purchased payable and other liabilities	(69,737)	(110,871)
Noncontrolling interests	(13,958)	(16,667)
The Company’s net interests in consolidated investment products	87,100	86,400
Other
Variable Interest Entity [Line Items]
Cash and cash equivalents	559	18,489
Investments	27,379	7,250
Other assets	403	48
Notes payable	0	0
Securities purchased payable and other liabilities	(146)	(764)
Noncontrolling interests	(36)	0
The Company’s net interests in consolidated investment products	$ 28,159	$ 25,023