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
	Mar. 31, 2018	Mar. 31, 2017
Calculation of net income (loss) per share:
Net income (loss)	$ 4,829	$ 2,341
Basic weighted average shares outstanding (in shares)	49,474	49,050
Basic income (loss) per share (in dollars per share)	$ 0.10	$ 0.05
Effect of stock options outstanding:
Basic weighted average shares outstanding (in shares)	49,474	49,050
Effect from dilutive shares and options outstanding (in shares)	550	784
Diluted weighted average shares (in shares)	50,024	49,834
Diluted income (loss) per share (in dollars per share)	$ 0.10	$ 0.05