Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income	$ 51,787	$ 98,227	$ 204,601	$ 392,355
Denominator:
Denominator for basic net earnings per share - weighted-average shares outstanding (shares)	124,515	123,255	123,896	123,835
Effect of dilutive employee stock awards (shares)	1,806	2,608	2,244	2,572
Denominator for net diluted earnings per share - weighted-average shares outstanding (shares)	126,321	125,863	126,140	126,407
Basic earnings per share (in dollars per share)	$ 0.42	$ 0.80	$ 1.65	$ 3.17
Diluted earnings per share (in dollars per share)	$ 0.41	$ 0.78	$ 1.62	$ 3.10
Anti-dilutive stock-based awards excluded from calculations	3,300		1,700