Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense	$ 73,082	$ 58,543
Effective tax rate	34.00%	33.00%
Federal statutory rate	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount	$ 5,900	$ 5,300
Undistributed Earnings of Foreign Subsidiaries	(4,100)	(3,500)
State income tax expense	3,416	3,215
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	2,266	$ 2,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	37,000
Second component of tax deductible goodwill, net of tax	$ 402