CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total	Preferred Stock Series B Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance (in shares) at Dec. 31, 2013			8,000,000	365,125,000
Balance at Dec. 31, 2013		$ 3,142,251	$ 80	$ 3,651	$ 2,972,369	$ (571,544)	$ 737,695
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing		0					0
Net income		313,504				313,504
Issuance of common stock, net of expenses (in shares)				5,305,000
Issuance of common stock, net of expenses		35,640		$ 50	35,590
Repurchase of shares of common stock (in shares)	[1]			(346,000)
Repurchase of shares of common stock	[1]	(2,688)		$ 0	(2,688)
Equity based compensation expense		8,581			8,581
Accrued dividends attributable to stock-based awards		(218)			(218)
Dividends declared on common stock		(294,792)				(294,792)
Dividends declared on preferred stock		(15,000)				(15,000)
Dividends attributable to dividend equivalents		(764)				(764)
Change in unrealized gains/(losses) on MBS and CRT securities, net		60,603					60,603
Change in unrealized gains/(losses) on derivative hedging instruments, net		(43,845)					(43,845)
Balance (in shares) at Dec. 31, 2014			8,000,000	370,084,000
Balance at Dec. 31, 2014		3,203,272	$ 80	$ 3,701	3,013,634	(568,596)	754,453
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing		4,537				(4,537)	4,537
Net income		313,226				313,226
Issuance of common stock, net of expenses (in shares)				809,000
Issuance of common stock, net of expenses		1,221		$ 5	1,216
Repurchase of shares of common stock (in shares)	[1]			(309,000)
Repurchase of shares of common stock	[1]	(2,273)			(2,273)
Equity based compensation expense		7,829			7,829
Accrued dividends attributable to stock-based awards		(450)			(450)
Dividends declared on common stock		(296,384)				(296,384)
Dividends declared on preferred stock		(15,000)				(15,000)
Dividends attributable to dividend equivalents		(1,041)				(1,041)
Change in unrealized gains/(losses) on MBS and CRT securities, net		(232,802)					(232,802)
Change in unrealized gains/(losses) on derivative hedging instruments, net		(10,337)					(10,337)
Balance (in shares) at Dec. 31, 2015			8,000,000	370,584,000
Balance at Dec. 31, 2015		2,967,261	$ 80	$ 3,706	3,019,956	(572,332)	515,851
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing		0					0
Net income		312,668				312,668
Issuance of common stock, net of expenses (in shares)				1,758,000
Issuance of common stock, net of expenses		4,660		$ 13	4,647
Repurchase of shares of common stock (in shares)	[1]			(488,000)
Repurchase of shares of common stock	[1]	(3,551)			(3,551)
Equity based compensation expense		8,695			8,695
Accrued dividends attributable to stock-based awards		(685)			(685)
Dividends declared on common stock		(297,046)				(297,046)
Dividends declared on preferred stock		(15,000)				(15,000)
Dividends attributable to dividend equivalents		(931)				(931)
Change in unrealized gains/(losses) on MBS and CRT securities, net		35,153					35,153
Change in unrealized gains/(losses) on derivative hedging instruments, net		22,678					22,678
Balance (in shares) at Dec. 31, 2016			8,000,000	371,854,000
Balance at Dec. 31, 2016		$ 3,033,902	$ 80	$ 3,719	$ 3,029,062	$ (572,641)	$ 573,682

[1] For the year ended December 31, 2016, includes approximately $3.6 million (487,559 shares) surrendered for tax purposes related to equity-based compensation awards. For the year ended December 31, 2015, includes approximately $2.3 million (309,206 shares) surrendered for tax purposes related to equity-based compensation awards. For the year ended December 31, 2014, includes approximately $2.7 million (345,559 shares) surrendered for tax purposes related to equity-based compensation awards.