Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income tax expense	$ 21,157	$ 43,358	$ 119,090	$ 155,609
Effective tax rate	24.00%	36.00%	31.00%	35.00%
Federal statutory rate			35.00%	35.00%
State income tax expense	$ 788	$ 2,775	$ 6,123	$ 9,335
Effective Income Tax Rate Reconciliation, Undistributed Earnings of Foreign Subsidiaries	3,443	409	12,364	6,610
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount	6,651		3,939
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount	3	4,332	13	14,515
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	2,320	$ 3,261	7,021	$ 10,049
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	42,000		42,000
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			764
Second component of tax deductible goodwill, net of tax	$ 1,207		$ 1,207