Earnings per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income	$ (609)	$ 5,149	$ 3,719	$ 2,654	$ 2,421	$ 4,658	$ 15,743	$ (726)	$ 10,913	$ 22,093	$ 18,354
Denominator (weighted average shares):
Basic weighted average common shares outstanding (in shares)									54,740	53,764	53,701
Weighted average effect of dilutive stock awards (in shares)									1,327	1,574	1,911
Diluted weighted average common shares outstanding (in shares)									56,067	55,338	55,612
Net income (loss) per share - basic (in dollars per share)	$ (0.01)	$ 0.09	$ 0.07	$ 0.05	$ 0.04	$ 0.09	$ 0.29	$ (0.01)	$ 0.20	$ 0.41	$ 0.34
Net income (loss) per share - diluted (in dollars per share)	$ (0.01)	$ 0.09	$ 0.07	$ 0.05	$ 0.04	$ 0.08	$ 0.28	$ (0.01)	$ 0.19	$ 0.40	$ 0.33