CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Cash Flows From Operating Activities:
Net income	$ 83,011	$ 79,510	$ 240,031	$ 239,754
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sales of MBS	(7,083)	(11,196)	(26,069)	(25,248)
(Gain)/loss on sales of real estate owned	(733)	129	(1,840)	102
Other-than-temporary impairment charges	485	0	485	705
Accretion of purchase discounts on MBS and CRT securities and residential whole loans			(64,093)	(73,192)
Amortization of purchase premiums on MBS			27,748	32,745
Depreciation and amortization on real estate, fixed assets and other assets			746	567
Equity-based compensation expense			4,143	3,600
Unrealized gain on residential whole loans at fair value			(25,529)	(3,872)
Increase in other assets			(47,761)	(23,451)
(Decrease)/increase in other liabilities			(9,025)	3,609
Net cash provided by operating activities			98,836	155,319
Cash Flows From Investing Activities:
Principal payments on MBS and CRT securities			2,581,507	2,323,214
Proceeds from sales of MBS			65,068	50,700
Purchases of MBS and CRT securities			(1,398,606)	(1,433,207)
Purchases of residential whole loans and capitalized advances			(367,740)	(458,146)
Principal payments on residential whole loans			70,729	27,051
Proceeds from sales of real estate owned			21,833	3,872
Redemption of Federal Home Loan Bank stock			49,595	0
Purchases of Federal Home Loan Bank stock			0	(10,617)
Additions to leasehold improvements, furniture and fixtures			(380)	(1,090)
Net cash provided by investing activities			1,022,006	501,777
Cash Flows From Financing Activities:
Principal payments on repurchase agreements and other advances			(62,376,619)	(75,970,367)
Proceeds from borrowings under repurchase agreements and other advances			61,685,547	75,659,218
Principal payments on securitized debt			(22,057)	(78,187)
Payments made for margin calls on repurchase agreements and interest rate swap agreements (“Swaps”)			(179,028)	(198,824)
Proceeds from reverse margin calls on repurchase agreements and Swaps			128,700	156,100
Proceeds from issuances of common stock			941	926
Dividends paid on preferred stock			(11,250)	(11,250)
Dividends paid on common stock and dividend equivalents			(223,385)	(222,989)
Net cash used in financing activities			(997,151)	(665,373)
Net increase/(decrease) in cash and cash equivalents			123,691	(8,277)
Cash and cash equivalents at beginning of period			165,007	182,437	$ 182,437
Cash and cash equivalents at end of period	288,698	174,160	288,698	174,160	165,007
Non-cash Investing and Financing Activities:
MBS and CRT securities recorded upon adoption of revised accounting standard for repurchase agreement financing			0	1,917,813
Repurchase agreements recorded upon adoption of revised accounting standard for repurchase agreement financing			0	1,519,593	1,500,000
Net (decrease)/increase in securities obtained as collateral/obligation to return securities obtained as collateral			(13,450)	25,150
Transfer from residential whole loans to real estate owned	24,812	5,892	69,803	12,894
Dividends and dividend equivalents declared and unpaid	$ 74,556	$ 74,560	$ 74,556	$ 74,560	$ 74,575