Consolidated K-Series - Condensed Statement of Operations of Consolidated K-Series (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Income Statements, Captions [Line Items]
Interest expense	$ 3,849	$ 3,463
NET INTEREST INCOME	17,642	21,601
Unrealized gain on multi-family loans and debt held in securitization trusts, net	818	13,628
Consolidated K-Series
Condensed Income Statements, Captions [Line Items]
Interest income	63,532	66,300
Interest expense	57,200	60,095
NET INTEREST INCOME	6,332	6,205
Unrealized gain on multi-family loans and debt held in securitization trusts, net	818	13,628
Net Income	$ 7,150	$ 19,833