Accumulated Other Comprehensive Income (Schedule of Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of revenue	$ 1,135,615	$ 1,041,359	$ 971,700
Tax expense (benefit)	79,854	94,426	80,695
Gains (losses), net of tax	582,131	427,792	377,047
Reclassification out of Accumulated Other Comprehensive Income | Foreign Currency Exchange Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of revenue	829	10,628	(976)
Tax expense (benefit)	158	2,467	(187)
Gains (losses), net of tax	$ 671	$ 8,161	$ (789)