Investment Securities, at Fair Value - Scheduled Maturity of CMBS (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value
Total	$ 41,677	$ 47,215
CMBS [Member]
Amortized Cost
Due within one year	0
Due after one year through five years	17,984
Due after five years through 10 years	12,011
Due after 10 years	13,311
Amortized Cost	43,306	48,297
Fair Value
Due within one year	0
Due after one year through five years	18,430
Due after five years through 10 years	9,336
Due after 10 years	13,911
Total	$ 41,677	$ 47,215