CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
MBS and GSE CRT pledged as collateral	$ 21,132,742	$ 17,082,825
Preferred Stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized	50,000,000	50,000,000
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	450,000,000	450,000,000
Common stock, shares issued	144,256,357	111,584,996
Common stock, shares outstanding	144,256,357	111,584,996
Series A Cumulative Redeemable Preferred Stock
Preferred Stock, dividend rate stated percentage	7.75%	7.75%
Preferred Stock, shares issued	5,600,000	5,600,000
Preferred Stock, shares outstanding	5,600,000	5,600,000
Preferred Stock, aggregate liquidation preference	$ 140,000	$ 140,000
Series B Cumulative Redeemable Preferred Stock
Preferred Stock, dividend rate stated percentage	7.75%	7.75%
Preferred Stock, shares issued	6,200,000	6,200,000
Preferred Stock, shares outstanding	6,200,000	6,200,000
Preferred Stock, aggregate liquidation preference	$ 155,000	$ 155,000
Series C Cumulative Redeemable Preferred Stock
Preferred Stock, dividend rate stated percentage	7.50%	7.50%
Preferred Stock, shares issued	11,500,000	11,500,000
Preferred Stock, shares outstanding	11,500,000	11,500,000
Preferred Stock, aggregate liquidation preference	$ 287,500	$ 287,500