Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating activities
Net income	$ 16,798	$ 67,239
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization of premium related to mortgage-backed securities	22,091	43,208
Reclassification of deferred swap loss	24,684
Amortization related to interest rate swap agreements	69	83
Share based compensation expense	860	629
Hedge ineffectiveness		116
Net gain on sale of mortgage-backed securities	(7,436)	(2,500)
Net (gain) loss on derivative instruments	41,615	(51)
Changes in operating assets and liabilities:
Decrease in accrued interest receivable	1,527	2,422
(Increase) decrease in other assets	(2)	88
Decrease in accrued interest payable	(4,804)	(2,552)
Increase (decrease) in accounts payable and other liabilities	4,052	(276)
Net cash provided by operating activities	99,454	108,406
Investing activities
Purchases of mortgage-backed securities	(948,925)	(1,316,188)
Principal repayments on mortgage-backed securities	768,532	1,534,530
Sales of mortgage-backed securities	960,291	132,630
Net payments on derivative instruments	(26,462)
Purchases of equity securities	(6,000)
Net cash provided by investing activities	747,436	350,972
Financing activities
Repurchase of common stock	(1,912)
Cash dividends paid	(53,782)	(74,656)
Proceeds from repurchase agreements	44,262,079	63,814,319
Principal repayments on repurchase agreements	(45,208,305)	(64,093,816)
Proceeds from dollar roll liability	241,121
Repayments on dollar roll liability	(592,947)
(Increase) decrease in restricted cash margin on derivatives	(6,212)	41,604
Net cash used in financing activities	(1,359,958)	(312,549)
Net increase (decrease) in cash and cash equivalents	(513,068)	146,829
Cash and cash equivalents, beginning of period	763,326	168,424
Cash and cash equivalents, end of period	250,258	315,253
Supplemental disclosure of cash flow information
Cash paid during the period for interest	47,915	55,777
Supplemental schedule of non-cash investing and financing activities
Obligation to brokers for purchase of unsettled mortgage-backed securities	157,387	1,229,848
Dividend payable	52,885
Preferred Stock
Supplemental schedule of non-cash investing and financing activities
Dividend payable	4,627	4,628
Common Stock
Supplemental schedule of non-cash investing and financing activities
Dividend payable	$ 48,258	$ 69,181