Income Taxes (Income Tax Expense Difference) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax expense at Federal statutory income tax rate	$ 28,798	$ 23,161	$ 28,429
International tax rate differential	(2,260)	(4,792)	(6,772)
Foreign source income, net of tax credits	7,559	2,449	5,195
State tax, net of federal	(200)	(416)	0
Unrecognized tax benefits	(5,555)	148	603
General business credits	(1,125)	(908)	(604)
Acquisition related expenses	0	453	590
Taxes on unremitted earnings	6,089	0	0
Valuation allowance change	171	(1,489)	388
Other	520	1,247	(17)
Total	$ 33,997	$ 19,853	$ 27,812