Accumulated Other Comprehensive Loss (After-tax Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ (3,988)	$ (11,964)	$ (2,700)	$ (12,468)
Other comprehensive income (loss) before reclassifications	[1]	(1,191)	(29)	(2,311)	475
Amounts reclassified from accumulated other comprehensive loss	[1]	(168)		(336)
Net current-period other comprehensive income (loss)	[1]	(1,359)	(29)	(2,647)	475
Ending balance	[1]	(5,347)	(11,993)	(5,347)	(11,993)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	0		0
Other comprehensive income (loss) before reclassifications	[1]	51		51
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0
Net current-period other comprehensive income (loss)	[1]	51		51
Ending balance	[1]	51		51
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(8,866)	(10,488)	(7,716)	(11,002)
Other comprehensive income (loss) before reclassifications	[1]	(1,123)	959	(2,273)	1,473
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0
Net current-period other comprehensive income (loss)	[1]	(1,123)	959	(2,273)	1,473
Ending balance	[1]	(9,989)	(9,529)	(9,989)	(9,529)
Investment in Convertible Preferred Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	257		344
Other comprehensive income (loss) before reclassifications	[1]	0		(87)
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0
Net current-period other comprehensive income (loss)	[1]	0		(87)
Ending balance	[1]	257		257
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	4,621	(1,476)	4,672	(1,466)
Other comprehensive income (loss) before reclassifications	[1]	(119)	(988)	(2)	(998)
Amounts reclassified from accumulated other comprehensive loss	[1]	(168)		(336)
Net current-period other comprehensive income (loss)	[1]	(287)	(988)	(338)	(998)
Ending balance	[1]	$ 4,334	$ (2,464)	$ 4,334	$ (2,464)

[1] All amounts are net of tax. Amounts in parentheses indicate debits