Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Line Items]
Tax rates	35.00%
Federal tax rate of deferred tax assets and liabilities	21.00%
Current year and prior year earnings of Company's foreign operations	$ 97,800
Foreign withholding taxes	$ 2,100
Estimated effective tax rate on continuing operations	32.50%	32.60%
Increase decrease in unrecognized tax benefits	$ 600
Foreign tax credits	20,000
Increase decrease in deferred tax liabilities	$ 500
Percentage of AETR increased	2.70%
Estimated foreign-derived intangible income deduction	$ 7,000
Percentage of AETR decreased	1.80%
Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax years	2007
Latest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax years	2018