CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total		Series A Preferred Stock	Series B Preferred Stock	Preferred Stock, Cumulative Redeemable - Liquidation Preference $25.00 per Share: Series A Preferred Stock	Preferred Stock, Cumulative Redeemable - Liquidation Preference $25.00 per Share: Series B Preferred Stock	Common Stock		Additional Paid-in Capital		Additional Paid-in Capital Series A Preferred Stock	Additional Paid-in Capital Series B Preferred Stock	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance at Dec. 31, 2012		$ 3,311,006				$ 38	$ 0	$ 3,575		$ 2,805,724				$ (260,308)	$ 761,977
Balance (in shares) at Dec. 31, 2012						3,840	0	357,546
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment on adoption of revised accounting standard for repurchase agreement financing		0													0
Net income		302,709												302,709
Issuance of stock, net of expenses		77,625	[1]		$ 193,316		$ 80	$ 97	[1]	77,528	[1]		$ 193,236
Issuance of common stock, net of expenses (in shares)							8,000	9,855	[1]
Redemption of Series A Preferred Stock				$ (92,053)		$ (38)						$ (92,015)
Redemption of Series A Preferred Stock (in shares)						(3,840)
Repurchase of shares of common stock	[1]	(16,281)						$ (21)		(16,260)
Repurchase of shares of common stock (in shares)	[1]							(2,276)
Equity based compensation expense		4,156								4,156
Dividends declared on common stock		(594,318)												(594,318)
Dividends declared on preferred stock		(13,750)												(13,750)
Dividends attributable to dividend equivalents		(1,930)												(1,930)
Issuance cost of redeemed Preferred stock		(3,947)												(3,947)
Change in unrealized gains/(losses) on MBS and CRT securities, net		(71,896)													(71,896)
Change in unrealized gains/(losses) on derivative hedging instruments, net		47,614													47,614
Balance at Dec. 31, 2013		3,142,251				$ 0	$ 80	$ 3,651		2,972,369				(571,544)	737,695
Balance (in shares) at Dec. 31, 2013						0	8,000	365,125
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 stock, net of expenses	[1]	35,640						$ 50		35,590
Issuance of common stock, net of expenses (in shares)	[1]							5,305
Repurchase of shares of common stock	[1]	(2,688)								(2,688)
Repurchase of shares of common stock (in shares)	[1]							(346)
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 at Dec. 31, 2014		3,203,272					$ 80	$ 3,701		3,013,634				(568,596)	754,453
Balance (in shares) at Dec. 31, 2014							8,000	370,084
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 stock, net of expenses	[1]	1,221						$ 5		1,216
Issuance of common stock, net of expenses (in shares)	[1]							809
Repurchase of shares of common stock	[1]	(2,273)								(2,273)
Repurchase of shares of common stock (in shares)	[1]							(309)
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 at Dec. 31, 2015		$ 2,967,261					$ 80	$ 3,706		$ 3,019,956				$ (572,332)	$ 515,851
Balance (in shares) at Dec. 31, 2015							8,000	370,584

[1] 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. For the year ended December 31, 2013, includes approximately $15.4 million (2,143,354 shares) repurchased through the Company’s publicly announced stock repurchase program and approximately $849,000 (132,276 shares) surrendered for tax purposes related to equity-based compensation awards.