Income Taxes (Schedule of Components of Deferred Income Tax Expense/(Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net effect of temporary differences	$ (5,774)	$ 7,214	$ (7,615)
Foreign tax credits	8,340	(6,869)	(17,874)
Retirement benefits	(502)	1,734	1,844
Net impact to operating loss carryforwards	(900)	(603)	(5,722)
Enacted changes in tax laws and rates	1,878	183	670
Adjustments to beginning-of-the-year valuation allowance balance for changes in circumstances	(3,522)	(88)	75
Deferred income tax provision	$ (480)	$ 1,571	$ (28,622)