Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net Income (Loss)	$ 7,695	$ 4,511	$ 13,306	$ 10,265
Denominator:
Weighted-average common shares outstanding, Basic (in shares)	109,555	110,214	110,353	109,951
Effect of potential dilutive common shares	3,564	3,509	3,508	2,854
Denominator:
Weighted-average common shares outstanding, Diluted (in shares)	113,119	113,723	113,861	112,805
Earnings Per Share, Basic	$ 0.07	$ 0.04	$ 0.12	$ 0.09
Earnings Per Share, Diluted	$ 0.07	$ 0.04	$ 0.12	$ 0.09