Real Estate Securities - Activity of Credit Component of Other-than-Temporary Impairments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Activity of the Credit Component of Other-than-Temporary Impairments
Balance at beginning of period	$ 28,198	$ 32,696	$ 28,277	$ 33,849
Initial credit impairments	0	226	291	226
Securities sold, or expected to sell	0	0	(261)	(348)
Securities with no outstanding principal at period end	0	(446)	(109)	(1,251)
Balance at End of Period	$ 28,198	$ 32,476	$ 28,198	$ 32,476