Stockholders' Equity (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	$ 754,453
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing	4,537	0
Net OCI during the period	4,375	54,490
Balance at end of period	758,828
Net Unrealized Gain/(Loss) on Available-for-Sale MBS and CRT Securities
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	813,515	752,912
OCI before reclassifications	39,035	69,260
Amounts reclassified from AOCI	(6,830)	(2,950)
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing	4,537
Net OCI during the period	36,742	66,310
Balance at end of period	850,257	819,222
Net Unrealized Loss on Swaps
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	(59,062)	(15,217)
OCI before reclassifications	(32,367)	(12,267)
Amounts reclassified from AOCI	0	447
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing	0
Net OCI during the period	(32,367)	(11,820)
Balance at end of period	(91,429)	(27,037)
Total AOCI
Components of accumulated other comprehensive income/(loss)
Balance at beginning of period	754,453	737,695
OCI before reclassifications	6,668	56,993
Amounts reclassified from AOCI	(6,830)	(2,503)
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing	4,537
Net OCI during the period	4,375	54,490
Balance at end of period	$ 758,828	$ 792,185

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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