Stockholders' Equity - Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Equity [Abstract]
Net income (loss)	$ 5,095	$ (12,497)	$ 13,585	$ (37,091)
Weighted average number of common shares outstanding (in shares)	31,458	30,890	31,361	30,848
Dilutive effect of restricted stock grants after application of the treasury stock method (in shares)	1,216	0	1,293	0
Dilutive shares outstanding (in shares)	32,674	30,890	32,654	30,848
Basic earnings (loss) per share (in dollars per share)	$ 0.16	$ (0.40)	$ 0.43	$ (1.20)
Diluted earnings (loss) per share (in dollars per share)	$ 0.16	$ (0.40)	$ 0.42	$ (1.20)