Summary of Significant Accounting Policies-New Accounting Standards and Interpretations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accounting Policies [Abstract]
MBS securities recorded upon adoption of revised accounting standard			$ 1,913,000
CRT securities recorded upon adoption of revised accounting standard			4,600
Repurchase agreements recorded upon adoption of revised accounting standard for repurchase agreement financing			1,519,593	$ 0
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing	$ 0	$ 0	$ 4,537	$ 0