Consolidated K-Series - Condensed Statement of Operations of Consolidated K-Series (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Income Statements, Captions [Line Items]
Total interest income	$ 79,766	$ 84,400	$ 161,392	$ 173,385
Interest expense	3,962	3,442	7,811	6,905
Total interest expense	63,102	64,097	127,086	131,481
NET INTEREST INCOME	16,664	20,303	34,306	41,904
Unrealized gain on multi-family loans and debt held in securitization trusts, net	784	5,418	1,602	19,046
NET INCOME ATTRIBUTABLE TO COMPANY	14,435	24,631	31,386	48,174
Consolidated K-Series
Condensed Income Statements, Captions [Line Items]
Interest income	61,769	62,984
Total interest income			125,301	129,284
Interest expense	55,224	56,992
Total interest expense			112,424	117,087
NET INTEREST INCOME	6,545	5,992	12,877	12,197
Unrealized gain on multi-family loans and debt held in securitization trusts, net	784	5,418	1,602	19,046
NET INCOME ATTRIBUTABLE TO COMPANY	$ 7,329	$ 11,410	$ 14,479	$ 31,243