Income Taxes US Tax Cuts and Jobs Act (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Overview [Member]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 66,713
Reduction of US Federal Corporate Tax Rate [Member]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 10,248
Transition Tax on Foreign Earnings [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	72,993
Utilization of Foreign Tax Credit Carryforwards	10,176
Utilization of Research and Development Credit Carryforwards	11,800
Acceleration of Depreciation [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	1,276
Change in Deferred Tax Assets due to 2017 Tax Act	1,914
Change in Other Current Liabilities due to 2017 Tax Act	3,190
Undistributed Foreign Earnings [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	3,968
Undistributed Earnings of Foreign Subsidiaries Subject To Transition Tax	943,704
Deferred Tax Liabilities, Undistributed Foreign Earnings	$ 30,734
Tax Act New Rate [Member] | Overview [Member]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	21.00%
Tax Act New Rate [Member] | Reduction of US Federal Corporate Tax Rate [Member]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	21.00%
Corporate Rate Reduction [Member] | Overview [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 10,248
Transition Tax [Member] | Overview [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	72,993
Incremental Taxes on Unremitted Foreign Earnings Release [Member] | Overview [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 3,968