Computation of Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income	$ 232,268	$ 67,652	$ 40,237	$ 16,181	$ 1,270	$ 24,844	$ 340,157	$ 42,295
Interest expense on Convertible Senior Notes, net of tax	107			180			457	1,669
Net income used for diluted earnings per share, if-converted method	$ 232,375			$ 16,361			$ 340,614	$ 43,964
Basic weighted-average common shares outstanding	42,105			41,642			42,093	40,520
Dilutive potential shares issuable from Convertible Senior Notes	218			410			340	1,282
Dilutive potential shares issuable from stock options and unvested RSUs	1,273			1,154			1,149	1,249
Diluted weighted-average common shares outstanding, if-converted	43,596			43,206			43,582	43,051
Potentially dilutive shares excluded from calculation due to anti-dilutive effect							4	198
Stock options
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares excluded from calculation due to anti-dilutive effect	7			223