Stockholders' Equity - Equity Capital Raising Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Issuance of stock	$ 52,960
Common stock repurchases, net	$ 0	$ 777
Common Stock
Class of Stock [Line Items]
Common stock repurchased (in shares)	4,400,000
Common stock repurchased, net (in shares)			(40,000)
Price per share (in dollars per share)			$ 19.42
Issuance of stock	$ 4
Common stock repurchases, net			$ (777)
Series C Preferred Stock
Class of Stock [Line Items]
Issuance of stock	$ 28,173	$ 129,221
Preferred C Underwritten Offering | Series C Preferred Stock
Class of Stock [Line Items]
Shares issued (in shares)			3,450,000
Price per share (in dollars per share)			$ 24.14
Issuance of stock			$ 83,282
Preferred C ATM Sales Agreement | Series C Preferred Stock
Class of Stock [Line Items]
Shares issued (in shares)			1,897,000
Price per share (in dollars per share)	$ 24.40		$ 24.70
Issuance of stock	$ 28,173		$ 46,856
Common stock ATM Sales Agreement | Common Stock
Class of Stock [Line Items]
Shares issued (in shares)			6,287,000
Common stock repurchased (in shares)	4,400,000
Price per share (in dollars per share)	$ 12.04		$ 8.68
Issuance of stock	$ 52,960		$ 54,575
Dividend Reinvestment Program | Series C Preferred Stock
Class of Stock [Line Items]
Shares issued (in shares)	1,154,000