Schedule of Mortgage Backed Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Disclosure Schedule Of Agency Securities Forward Purchase Commitments [Abstract]
TBA dollar roll securities - Face	$ 3,600,000	$ 600,000
TBA dollar roll securities - Cost	3,723,183	632,270
TBA dollar roll securities - Fair Market Value	3,703,228	627,187
TBA dollar roll securities - Net Asset (Liability)	$ (19,955)	$ (5,083)