Stockholders' Equity (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Components of accumulated other comprehensive income/(loss)
Accumulated other comprehensive income/(loss), beginning balance					$ 737,695
Other Comprehensive Income/(Loss)	58,848		(223,468)		113,338		(93,073)
Accumulated other comprehensive income/(loss), ending balance	851,033				851,033
Net Unrealized Gain on Available-for-Sale MBS
Components of accumulated other comprehensive income/(loss)
Accumulated other comprehensive income/(loss), beginning balance	819,222		942,887		752,912		824,808
OCI before reclassifications	93,230		(238,762)		162,491		(119,383)
Amounts reclassified from AOCI	(6,748)	[1]	(3,254)	[1]	(9,699)	[1]	(4,554)	[1]
Other Comprehensive Income/(Loss)	86,482	[2]	(242,016)	[2]	152,792	[2]	(123,937)	[2]
Accumulated other comprehensive income/(loss), ending balance	905,704		700,871		905,704		700,871
Net Unrealized (Loss)/Gain on Swaps
Components of accumulated other comprehensive income/(loss)
Accumulated other comprehensive income/(loss), beginning balance	(27,037)		(50,515)		(15,217)		(62,831)
OCI before reclassifications	(27,634)		18,548		(39,901)		30,864
Amounts reclassified from AOCI	0	[1]	0	[1]	447	[1]	0	[1]
Other Comprehensive Income/(Loss)	(27,634)	[2]	18,548	[2]	(39,454)	[2]	30,864	[2]
Accumulated other comprehensive income/(loss), ending balance	(54,671)		(31,967)		(54,671)		(31,967)
Total AOCI
Components of accumulated other comprehensive income/(loss)
Accumulated other comprehensive income/(loss), beginning balance	792,185		892,372		737,695		761,977
OCI before reclassifications	65,596		(220,214)		122,590		(88,519)
Amounts reclassified from AOCI	(6,748)	[1]	(3,254)	[1]	(9,252)	[1]	(4,554)	[1]
Other Comprehensive Income/(Loss)	58,848	[2]	(223,468)	[2]	113,338	[2]	(93,073)	[2]
Accumulated other comprehensive income/(loss), ending balance	$ 851,033		$ 668,904		$ 851,033		$ 668,904

[1] See separate table below for details about these reclassifications.

[2] For further information regarding changes in OCI, see the Company’s consolidated statement of comprehensive income/(loss).