Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows From Operating Activities:
Net income	$ 250,349	$ 589,205	$ 362,686
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Accretion) amortization of investment discounts/premiums, net	3,813	(72,569)	(80,586)
Accretion (amortization) of deferred financing costs and securitized debt discounts/premiums, net	17,145	11,552	17,671
Net unrealized losses (gains) on derivatives	(67,385)	103,496	(34,369)
Net realized losses (gains) on option contracts settled		1,246
Proceeds (payments) for derivative sales and settlements	(13,495)	(6,923)
Margin (paid) received on derivatives	82,671	(186,462)
Net unrealized losses (gains) on financial instruments at fair value	158,433	(193,534)	44,277
Net realized losses (gains) on sales of investments	(77,074)	(91,709)	(68,107)
Realized losses on principal write-downs of Non-Agency RMBS			18,316
(Gains) losses on deconsolidation	256	(47,846)
Net other-than-temporary credit impairment losses	67,444	63,992	45,167
(Gain) loss on extinguishment of debt	5,930	2,184
Provision for loan losses, net		(232)	(1,799)
Equity-based compensation expense	1,979	956	691
Changes in operating assets:
Decrease (increase) in accrued interest receivable, net	4,852	(37,570)	6,336
Decrease (increase) in other assets	(42,738)	16,471	(13)
Changes in operating liabilities:
Increase (decrease) in accounts payable and other liabilities	8,935	608	691
Increase (decrease) in investment management fees and expenses payable to affiliate	(10,357)	4,699	(2,017)
Increase (decrease) in accrued interest payable, net	5,544	25,213	(4,124)
Net cash provided by (used in) operating activities	396,302	182,777	304,820
Cash Flows From Investing Activities:
Net cash provided by (used in) investing activities	2,037,911	(5,778,558)	305,099
Cash Flows From Financing Activities:
Proceeds from repurchase agreements	41,644,280	27,128,227	7,879,361
Payments on repurchase agreements	(42,660,323)	(20,331,406)	(7,748,825)
Payments on repurchase of common stock	(250,000)
Payment of deferred financing costs	0	0	0
Proceeds from securitized debt borrowings, collateralized by loans held for investment	1,483,301	43,981
Payments on securitized debt borrowings, collateralized by loans held for investment	(2,138,623)	(341,313)	(499,549)
Payments on securitized debt borrowings, collateralized by Non-Agency RMBS	(182,217)	(185,369)	(414,690)
Repurchase of securitized debt borrowings, collateralized by Non-Agency RMBS		(56,072)
Common dividends paid	(381,189)	(575,276)	(369,740)
Net cash provided by (used in) financing activities	(2,484,771)	5,682,772	(1,153,443)
Net increase (decrease) in cash and cash equivalents	(50,558)	86,991	(543,524)
Cash and cash equivalents at beginning of period	164,620	77,629	621,153
Cash and cash equivalents at end of period	114,062	164,620	77,629
Supplemental disclosure of cash flow information:
Interest received	881,403	577,123	437,533
Interest paid	236,676	111,020	88,455
Management fees and expenses paid	34,966	27,815	27,969
Non-cash investing activities:
Receivable for investments sold		1,572,056	253,541
Payable for investments purchased	(560,641)	(1,845,282)
Net change in unrealized gain (loss) on available-for sale securities	(272,889)	55,877	867
Non-cash financing activities:
Common dividends declared, not yet paid	90,097	92,483	297,904
Agency MBS - Residential [Member]
Cash Flows From Investing Activities:
Purchases	(6,590,731)	(8,860,042)	(2,068,870)
Sales	7,563,771	2,555,570	1,037,371
Principal payments	1,061,193	512,202	479,650
Non-Agency RMBS [Member]
Cash Flows From Investing Activities:
Purchases	(850,750)	(365,240)	(317,299)
Sales	158,404	513,030	191,437
Principal payments	385,988	323,900	475,127
Securitized Loans [Member]
Cash Flows From Investing Activities:
Purchases	(281,811)
Principal payments	699,118	316,372	$ 507,683
Variable Interest Entities, Primary Beneficiary, Aggregated Disclosure [Member]
Cash Flows From Investing Activities:
Acquisition of investments in consolidated VIEs	(109,872)	(774,350)
Disposition of investments in consolidated VIEs	2,601
Acquisition of investments in consolidated VIEs
Securitized loans held for investment, at fair value	295,225	4,722,825
Other assets		84,830
Securitized debt at fair value	(185,353)	$ 4,033,304
Disposition of investments in consolidated VIEs
Non-agency RMBS, at fair value	49,118
Securitized loans held for investment, at fair value	(287,806)
Securitized debt at fair value	$ 236,087