CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total	Preferred Stock Preferred Stock 7.50% Series B Cumulative Redeemable - Liquidation Preference $25.00 per Share	Common Stock		Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance (in shares) at Dec. 31, 2017			8,000,000	397,831,000
Balance at Dec. 31, 2017		$ 3,261,636	$ 80	$ 3,978		$ 3,227,304	$ (578,950)	$ 609,224
Increase (Decrease) in Stockholders' Equity
Net income		83,395					83,395
Issuance of common stock, net of expenses (in shares)				849,000
Issuance of common stock, net of expenses		1,230		$ 6		1,224
Repurchase of shares of common stock (in shares)	[1]			(251,000)
Repurchase of shares of common stock	[1]	(1,957)				(1,957)
Equity based compensation expense		549				549
Accrued dividends attributable to stock-based awards		430				430
Dividends declared on common stock ($0.20 per share)		(79,686)					(79,686)
Dividends declared on preferred stock ($0.46875 per share)		(3,750)					(3,750)
Dividends attributable to dividend equivalents		(217)					(217)
Change in unrealized gains on MBS, net		(46,163)						(46,163)
Derivative hedging instrument fair value changes, net		19,669						19,669
Balance (in shares) at Mar. 31, 2018			8,000,000	398,429,000
Balance at Mar. 31, 2018		3,235,431	$ 80	$ 3,984		3,227,550	(578,913)	582,730
Increase (Decrease) in Stockholders' Equity
Adjustments related to tax withholding for share-based compensation				$ 2,000
Shares paid for tax withholding for share based compensation (in shares)				250,946
Balance (in shares) at Dec. 31, 2018			8,000,000	449,787,000
Balance at Dec. 31, 2018		3,416,101	$ 80	$ 4,498		3,623,275	(632,040)	420,288
Increase (Decrease) in Stockholders' Equity
Net income		88,857					88,857
Issuance of common stock, net of expenses (in shares)				1,066,000
Issuance of common stock, net of expenses		$ 551		$ 7		544
Repurchase of shares of common stock (in shares)		0		(370,000)	[1]
Repurchase of shares of common stock	[1]	$ (2,610)				(2,610)
Equity based compensation expense		992				992
Accrued dividends attributable to stock-based awards		435				435
Dividends declared on common stock ($0.20 per share)		(90,097)					(90,097)
Dividends declared on preferred stock ($0.46875 per share)		(3,750)					(3,750)
Dividends attributable to dividend equivalents		(256)					(256)
Change in unrealized gains on MBS, net		5,094						5,094
Derivative hedging instrument fair value changes, net		(10,786)						(10,786)
Balance (in shares) at Mar. 31, 2019			8,000,000	450,483,000
Balance at Mar. 31, 2019		$ 3,404,531	$ 80	$ 4,505		$ 3,622,636	$ (637,286)	$ 414,596
Increase (Decrease) in Stockholders' Equity
Adjustments related to tax withholding for share-based compensation				$ 2,600
Shares paid for tax withholding for share based compensation (in shares)				370,244

[1] For the three months ended March 31, 2019 and 2018, includes approximately $2.6 million (370,244 shares) and $2.0 million (250,946 shares), respectively surrendered for tax purposes related to equity-based compensation awards.