Financial Derivatives (TBAs) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Financial derivatives–assets, at fair value-	$ 12,740	$ 20,001
Derivative Liability	25,572	$ 20,806
Derivative Assets (Liabilities), at Fair Value, Net	(12,832)
TBA securities
Derivative [Line Items]
Notional Amount	836,997
Derivative, Cost Basis	(874,026)
Market Value Underlying	(874,788)
Derivative Assets (Liabilities), at Fair Value, Net	(762)
TBA securities | Long
Derivative [Line Items]
Notional Amount	28,789
Derivative, Cost Basis	29,709
Market Value Underlying	29,752
Derivative Assets (Liabilities), at Fair Value, Net	43
TBA securities | Short
Derivative [Line Items]
Notional Amount	865,786
Derivative, Cost Basis	(903,735)
Market Value Underlying	(904,540)
Derivative Assets (Liabilities), at Fair Value, Net	(805)
Financial Derivatives - Assets | TBA securities | Long
Derivative [Line Items]
Notional Amount	28,789
Derivative, Cost Basis	29,709
Market Value Underlying	29,752
Financial derivatives–assets, at fair value-	43
Financial Derivatives - Assets | TBA securities | Short
Derivative [Line Items]
Notional Amount	136,628
Derivative, Cost Basis	(141,297)
Market Value Underlying	(141,198)
Financial derivatives–assets, at fair value-	99
Financial Derivatives - Liabilities | TBA securities | Short
Derivative [Line Items]
Notional Amount	729,158
Derivative, Cost Basis	(762,438)
Market Value Underlying	(763,342)
Derivative Liability	$ (904)