Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets [Abstract]
Cash	$ 328,936	$ 295,602
Cash collateral posted to counterparties	49,180	14,758
Mortgage-backed securities (including pledged of $2,173,333 and $2,467,859, respectively), at fair value	2,380,373	2,596,255
Mortgage loans held for investment, at fair value	5,749	6,264
Receivable for sales pending settlement	5,067	150,432
Derivative assets	109,746	11,342
Accrued interest receivable	15,480	14,388
Other assets, net	6,577	6,394
Total assets	2,901,108	3,095,435
Liabilities:
Repurchase agreements	2,032,089	2,437,163
Payable for purchases pending settlement	24,455	5
Derivative liabilities	19,866	1,634
Derivative Asset, Collateral, Obligation to Return Cash, Offset	83,776	7,681
Accrued interest payable	418	1,410
Accrued dividends payable	5,639	5,814
Other liabilities	3,589	8,275
Total liabilities	2,169,832	2,461,982
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, par value $0.01 per share; 50,000,000 shares authorized; 4,460,000 and 7,248,330 shares issued and outstanding, respectively ($111,500 and $181,208 aggregate liquidation preference, respectively)	107,843	174,564
Common stock, par value $0.01 per share, 90,000,000 shares authorized; 30,879,569 and 23,697,970 shares issued and outstanding, respectively	309	237
Additional paid-in capital	997,326	869,495
Accumulated other comprehensive income	15,105	80,261
Accumulated deficit	(389,307)	(491,104)
Total shareholders’ equity	731,276	633,453
Total liabilities and shareholders’ equity	$ 2,901,108	$ 3,095,435