Accumulated Other Comprehensive Income (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of revenue	$ (260,353)			$ (239,805)			$ (767,062)	$ (722,675)
Tax expense (benefits)	(23,960)			(15,825)			(76,464)	(59,327)
Gain (loss), net of tax	108,838	$ 125,701	$ 102,709	93,214	$ 108,680	$ 89,476	337,248	291,370
Accumulated Net Gain (Loss) from Cash Flow Hedges | Amount of (loss) gain reclassified from accumulated other comprehensive income into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of revenue	3,171			256			7,091	(2,412)
Tax expense (benefits)	688			153			1,295	(476)
Gain (loss), net of tax	$ 2,483			$ 103			$ 5,796	$ (1,936)