Fair Value of Financial Instruments - Losses Incurred for Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Residential Mortgage Loans Held In Securitization Trusts Impaired Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gain (loss) for assets measured at fair value on a non-recurring basis	$ (1,261)	$ (998)	$ (701)
Real Estate Owned Held In Residential Securitization Trusts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gain (loss) for assets measured at fair value on a non-recurring basis	$ 100	$ (103)	$ (433)