Income Taxes - Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income Tax Provision at the Federal Statutory Tax Rate	$ 21,229	$ 29,403	$ 24,578
Transition tax	18,388	0	0
Revaluation of deferred tax assets and liabilities	4,470	0	0
Non-deductible acquisition expenses	4,779	696	122
Share-based compensation	(1,419)	0	0
Differences in Tax Rates on Foreign Earnings and Remittances	(2,663)	(2,862)	(5,097)
Foreign Dividends	0	2,939	2,690
Excess Foreign Tax Credit Utilization	(2,761)	(5,493)	(4,141)
Research and Development Activities Credit Utilization	235	238	245
Uncertain Tax Positions	(651)	(833)	226
Domestic Production Activities Deduction	(1,155)	(875)	(910)
State Income Tax Provisions, Net	569	357	133
Non-deductible Entertainment and Business Meals Expense	248	238	249
Miscellaneous Items, Net	854	(106)	180
Income Tax Expense (Benefit), Total	$ 41,653	$ 23,226	$ 17,785