Net Income (Loss) Per Share - (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator (both basic and diluted)
Net income (loss) relevant to common stockholders	$ (25,920)	$ (7,804)	$ 36,133	$ 69,805	$ (33,724)	$ 105,938
Denominator
Denominator for basic earnings (loss) per share (in shares)	100,821		100,425		100,754	100,329
Denominator for diluted income (loss) per share (in shares)	100,821		104,379		100,754	104,181
Basic income (loss) per common share (in dollars per share)	$ (0.26)		$ 0.36		$ (0.33)	$ 1.06
Diluted income (loss) per common share (in dollars per share)	$ (0.26)		$ 0.35		$ (0.33)	$ 1.02
Antidilutive securities excluded from computation of earnings per share, amount (in shares)					6,544	0
Stock options
Denominator
Dilutive effect of share based payment (in shares)	0		3,294		0	3,252
Restricted stock units
Denominator
Dilutive effect of share based payment (in shares)	0		211		0	182
Performance stock units
Denominator
Dilutive effect of share based payment (in shares)	0		449		0	418
Stock options
Denominator
Antidilutive securities excluded from computation of earnings per share, amount (in shares)					4,224	0
Restricted stock units
Denominator
Antidilutive securities excluded from computation of earnings per share, amount (in shares)					1,269	0
Performance stock units
Denominator
Antidilutive securities excluded from computation of earnings per share, amount (in shares)					1,051	0