Variable Interest Entities - Summary of Assets and Liabilities of Variable Interest Entities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Cash and restricted cash	$ 41,823	$ 55,728
Total assets	8,794,143	9,030,441
Loans payable to noncontrolling interests	45,662	42,195
Other liabilities	45,101	43,950
Total liabilities	3,483,593	3,475,488
Variable Interest Entity [Member]
Variable Interest Entity [Line Items]
Investments, at fair value	8,025	17,136
Investments, at cost	63,511	63,550
Cash and restricted cash	497	4,976
Total assets	72,033	85,662
Loans payable to noncontrolling interests	45,662	42,195
Other liabilities	195	131
Total liabilities	$ 45,857	$ 42,326