Stockholders' Equity - Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity [Abstract]
Net income	$ 8,520	$ 12,583	$ 26,827	$ 35,631
Weighted average number of common shares outstanding (in shares)	30,581	30,219	30,547	30,219
Dilutive effect of restricted stock grants after application of the treasury stock method (in shares)	271	419	282	356
Dilutive shares outstanding (in shares)	30,852	30,638	30,829	30,575
Basic earnings per share (in dollars per share)	$ 0.28	$ 0.42	$ 0.88	$ 1.18
Diluted earnings per share (in dollars per share)	$ 0.28	$ 0.41	$ 0.87	$ 1.17