Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator for basic and diluted net (loss)/income per share:
Net (loss)/income from continuing operations	$ (5,524)	$ 58,532	$ (3,791)	$ 86,894
Loss from discontinued operations, net of tax	(48)	(16)	(94)	(91)
Net (loss)/income	$ (5,572)	$ 58,516	$ (3,885)	$ 86,803
Denominator:
Weighted-average shares for basic income per share (in shares)	80,473	81,284	80,326	81,269
Dilutive effect of stock options and restricted stock units (in shares)	0	1,156	0	1,416
Weighted-average shares for diluted income per share (in shares)	80,473	82,440	80,326	82,685
Basic:
Net (loss)/income from continuing operations (usd per share)	$ (0.07)	$ 0.72	$ (0.05)	$ 1.07
Loss from discontinued operations, net of tax (usd per share)	0	0	0	0
Net (loss)/income (usd per share)	(0.07)	0.72	(0.05)	1.07
Diluted:
Net income from continuing operations (usd per share)	(0.07)	0.71	(0.05)	1.05
Loss from discontinued operations, net of tax (usd per share)	0	0	0	0
Net (loss)/income (usd per share)	$ (0.07)	$ 0.71	$ (0.05)	$ 1.05
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		100