Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 32,547	$ 60,193	$ 89,426	$ 133,275
Effective tax rate	23.00%	36.00%	25.00%	35.00%
Federal statutory rate		35.00%	21.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		$ 5,200	$ 16,100	$ 7,500
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount			8,300
Undistributed Earnings of Foreign Subsidiaries		(2,600)	(5,800)	(6,700)
State income tax expense	$ 2,300	2,600	6,200	6,000
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount		$ 4,400		$ 10,300
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	15,600		15,600
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			(15,600)
Second component of tax deductible goodwill, net of tax	$ 700		$ 700