Earnings (Loss) Per Share (EPS) - Schedule of Diluted Earnings Per Shares Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Calculation of net income (loss) per share:
Net income (loss)	$ 15,534	$ 9,626	$ 6,583	$ 3,534	$ 16,209	$ 31,743	$ 5,795
Basic weighted average shares outstanding (in shares)	49,559			49,133		49,527	49,100
Basic income (loss) per share (in dollars per share)	$ 0.31	$ 0.19	$ 0.13	$ 0.07	$ 0.33	$ 0.64	$ 0.12
Effect of stock options outstanding:
Basic weighted average shares outstanding (in shares)	49,559			49,133		49,527	49,100
Effect from dilutive shares and options outstanding (in shares)	558			826		517	769
Diluted weighted average shares (in shares)	50,117			49,959		50,044	49,869
Diluted income (loss) per share (in dollars per share)	$ 0.31	$ 0.19	$ 0.13	$ 0.07	$ 0.32	$ 0.63	$ 0.12