Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ (11,964)	$ (18,327)	$ (12,468)	$ (20,939)
Other comprehensive income (loss) before reclassifications	[1]	(29)	1,289	475	4,083
Amounts reclassified from accumulated other comprehensive income (loss)	[1]		(56)		(238)
Other comprehensive income (loss)	[1]	(29)	1,233	475	3,845
Ending balance	[1]	(11,993)	(17,094)	(11,993)	(17,094)
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	0	(51)	0	(111)
Other comprehensive income (loss) before reclassifications	[1]	0	60	0	120
Amounts reclassified from accumulated other comprehensive income (loss)	[1]		0		0
Other comprehensive income (loss)	[1]	0	60	0	120
Ending balance	[1]	0	9	0	9
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(10,488)	(9,536)	(11,002)	(12,041)
Other comprehensive income (loss) before reclassifications	[1]	959	52	1,473	2,557
Amounts reclassified from accumulated other comprehensive income (loss)	[1]		0		0
Other comprehensive income (loss)	[1]	959	52	1,473	2,557
Ending balance	[1]	(9,529)	(9,484)	(9,529)	(9,484)
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]			0	126
Other comprehensive income (loss) before reclassifications	[1]			0	0
Amounts reclassified from accumulated other comprehensive income (loss)	[1]				(126)
Other comprehensive income (loss)	[1]			0	(126)
Ending balance	[1]	0	0	0	0
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(1,476)	(8,740)	(1,466)	(8,913)
Other comprehensive income (loss) before reclassifications	[1]	(988)	1,177	(998)	1,406
Amounts reclassified from accumulated other comprehensive income (loss)	[1]		(56)		(112)
Other comprehensive income (loss)	[1]	(988)	1,121	(998)	1,294
Ending balance	[1]	$ (2,464)	$ (7,619)	$ (2,464)	$ (7,619)

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