Fair Value Measures - Fair Value of Assets and Liabilities, Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Derivative assets	$ 199	$ 1,892
Liabilities:
Derivative liabilities	(3,547)	(6,922)
Fair Value, Measurements, Recurring [Member]
Assets:
CMBS	47,215	53,304
Derivative assets	199	1,892
Total assets	47,414	55,196
Liabilities:
Derivative liabilities	(3,547)	(6,922)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets:
CMBS	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets:
CMBS	0	0
Derivative assets	199	1,892
Total assets	199	1,892
Liabilities:
Derivative liabilities	(3,547)	(6,922)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets:
CMBS	47,215	53,304
Derivative assets	0	0
Total assets	47,215	53,304
Liabilities:
Derivative liabilities	$ 0	$ 0