Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Unrecognized Tax Benefits	$ 24,361	$ 31,534	$ 36,935	$ 44,701
Unrecognized Tax Benefits, Interest on Income Taxes Expense	(2,792)	(1,946)	(3,247)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3,301	6,881
Operating Loss Carryforwards		11,940
Deferred Tax Liabilities, Undistributed Foreign Earnings	3,200,000
Income Taxes Paid, Net	231,183	$ 190,109	$ 182,668
International [Member]
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Amount	327,568
Tax Credit Carryforward, Subject to Expiration	9,787
Tax Credit Carryforward, No Expiration	317,781
Tax Credit Carryforward, Deferred Tax Asset	105,534
Other Tax Carryforward, Valuation Allowance	$ 6,624