Significant Accounting Policies - Authorized Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended				12 Months Ended
	Aug. 10, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Common stock, shares authorized (in shares)		32,000,000				32,000,000	32,000,000
Common stock, par value (in dollars per share)		$ 0.01				$ 0.01	$ 0.01
Common stock, shares issued (in shares)		24,418,939				24,418,939	21,964,809
Common stock, shares outstanding (in shares)		24,418,939				24,418,939	21,964,809
Issuance of common stock in public offering (in shares)	2,185,000
Net proceeds from issuance of common stock	$ 220,200					$ 220,248	$ 0	$ 0
Payments of stock issuance costs	$ 9,200
Preferred stock, shares authorized		8,000,000				8,000,000	8,000,000
Preferred stock, shares issued		0				0	0
Preferred stock, shares outstanding		0				0	0
Dividends declared, per share		$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 2.40	$ 2.10	$ 1.50
Dividends paid, per share		$ 0.60	$ 0.60	$ 0.60	$ 0.60