CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows From Operating Activities:
Net income	$ 313,504	$ 302,709	$ 306,839
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sales of MBS and U.S. Treasury securities	(37,497)	(25,825)	(9,001)
Other-than-temporary impairment charges	0	0	1,200
Accretion of purchase discounts on MBS and CRT securities and residential whole loans	(89,182)	(73,447)	(38,263)
Amortization of purchase premiums on MBS	32,052	58,207	52,298
Depreciation and amortization on real estate, fixed assets and other assets	1,191	5,831	3,534
Equity-based compensation expense	8,581	4,158	6,488
Unrealized loss on residential whole loans at fair value	96	0	0
Unrealized gains on derivative instruments	(1,673)	(1,111)	(9,593)
Decrease/(increase) in interest receivable	4,561	8,180	(1,160)
Increase in prepaid and other assets	(12,684)	(5,549)	(12,767)
Realized loss on TBA short positions	0	7,517	0
(Decrease)/increase in accrued expenses and other liabilities, and excise tax and interest	(8,301)	3,610	3,820
Increase in accrued interest payable on financial instruments	45,165	13,808	6,992
Net cash provided by operating activities	255,813	298,088	310,387
Cash Flows From Investing Activities:
Principal payments on MBS and CRT securities	1,939,948	2,770,710	2,671,137
Proceeds from sale of MBS and U.S. Treasury securities	123,910	574,869	268,859
Purchases of MBS and CRT securities	(1,261,646)	(1,744,605)	(3,589,981)
Purchases of residential whole loans	(356,440)	0	0
Principal payments on residential whole loans	6,017	0	0
Additions to leasehold improvements, furniture, fixtures and real estate investment	(786)	(373)	(443)
Net cash provided by/(used in) investing activities	451,003	1,600,601	(650,428)
Cash Flows From Financing Activities:
Principal payments on repurchase agreements	(75,939,948)	(69,851,602)	(63,237,681)
Proceeds from borrowings under repurchase agreements	75,868,039	69,438,427	64,176,994
Proceeds from issuance of securitized debt	0	129,314	186,691
Principal payments on securitized debt	(254,078)	(409,606)	(415,395)
Payments made on obligation to return securities obtained as collateral	0	(246,850)	0
Maturity of obligation to return securities obtained as collateral	0	(275,402)	0
Payments made for resecuritization related costs	0	0	(1,814)
Proceeds from issuance of Senior Notes	0	0	100,000
Payments made for Senior Notes related costs	0	0	(3,415)
Cash disbursements on financial instruments underlying Linked Transactions	(6,750,803)	(419,802)	(585,393)
Cash received from financial instruments underlying Linked Transactions	6,336,872	405,436	462,889
Payments made for margin calls on repurchase agreements and Swaps	(208,600)	(69,902)	(2,390)
Proceeds from reverse margin calls on repurchase agreements and Swaps	132,800	22,809	12,890
Settlement of TBA short positions	0	(7,517)	0
Proceeds from issuances of common stock	35,639	77,625	13,038
Payments made for redemption of Series A Preferred Stock	0	(96,000)	0
Proceeds from issuance of Series B Preferred Stock	0	200,000	0
Payments made for preferred stock offering costs	0	(6,684)	0
Payments made to repurchase common stock	0	(16,281)	(9,713)
Dividends paid on preferred stock	(15,000)	(13,750)	(8,160)
Dividends paid on common stock and DERs	(294,670)	(594,827)	(341,229)
Net cash (used in)/provided by financing activities	(1,089,749)	(1,734,612)	347,312
Net (decrease)/increase in cash and cash equivalents	(382,933)	164,077	7,271
Cash and cash equivalents at beginning of period	565,370	401,293	394,022
Cash and cash equivalents at end of period	182,437	565,370	401,293
Supplemental Disclosure of Cash Flow Information:
Interest paid	160,935	162,186	161,657
Non-cash Investing and Financing Activities:
MBS recorded upon de-linking of Linked Transactions	86,449	0	175,194
Repurchase agreements recorded upon de-linking of Linked Transactions	49,095	0	0
Net increase in securities obtained as collateral/obligation to return securities obtained as collateral	135,165	401,135	202,432
Transfer from residential whole loans to real estate owned	2,904	0	0
Dividends and DERs declared and unpaid	$ 74,529	$ 73,643	$ 72,222