Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets [Abstract]
Mortgage-backed securities (including pledged of $5,024,625 and $3,511,604, respectively)	$ 5,188,163	$ 3,749,464
Mortgage loans held for investment, net	9,405	11,527
Cash and cash equivalents	62,582	34,598
Restricted cash	71,648	54,106
Derivative assets	4,290	6,563
Accrued interest receivable	26,209	21,019
Other assets, net	8,307	8,812
Total assets	5,370,604	3,886,089
Liabilities:
Repurchase agreements	4,752,348	3,267,984
Payable for unsettled securities	6,180	58,915
Non-recourse collateralized financing	2,733	3,458
Derivative liabilities	974	1,218
Accrued interest payable	15,585	10,308
Accrued dividends payable	6,280	13,810
Other liabilities	3,516	3,243
Total liabilities	4,787,616	3,358,936
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, par value $0.01 per share; 50,000,000 shares authorized; 6,788,330 and 5,954,594 shares issued and outstanding, respectively ($169,708 and $148,865 aggregate liquidation preference, respectively)	162,807	142,883
Common stock, par value $0.01 per share, 90,000,000 shares authorized; 22,945,993 and 20,939,073 shares issued and outstanding, respectively	229	209
Additional paid-in capital	858,347	818,861
Accumulated other comprehensive income (loss)	173,806	(35,779)
Accumulated deficit	(612,201)	(399,021)
Total shareholders’ equity	582,988	527,153
Total liabilities and shareholders’ equity	$ 5,370,604	$ 3,886,089