Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net income	$ 62,766	$ 112,906	$ 152,814	$ 294,128
Denominator:
Denominator for basic net earnings per share - weighted-average shares outstanding (shares)	124,230	123,522	123,580	124,128
Effect of dilutive employee stock awards (shares)	1,773	2,213	2,439	2,531
Denominator for net diluted earnings per share - weighted-average shares outstanding (shares)	126,003	125,735	126,019	126,659
Basic earnings per share (in dollars per share)	$ 0.51	$ 0.91	$ 1.24	$ 2.37
Diluted earnings per share (in dollars per share)	$ 0.50	$ 0.90	$ 1.21	$ 2.32
Anti-dilutive stock-based awards excluded from calculations	3,300		2,000