Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net Income (Loss)	$ (35,689)	$ 3,006
Denominator:
Weighted-average common shares outstanding, Basic (in shares)	109,358	111,464
Effect of potential dilutive common shares	0	3,861
Denominator:
Weighted-average common shares outstanding, Diluted (in shares)	109,358	115,325
Earnings Per Share, Basic	$ (0.33)	$ 0.03
Earnings Per Share, Diluted	$ (0.33)	$ 0.03