Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ (17,094)	$ (55,159)	$ (20,939)	$ (54,595)
Other comprehensive income (loss) before reclassifications	[1]	(155)	(2,215)	3,926	(2,609)
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	(56)	(85)	(292)	(255)
Other comprehensive income (loss)	[1]	(211)	(2,300)	3,634	(2,864)
Ending balance	[1]	(17,305)	(57,459)	(17,305)	(57,459)
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	9	(242)	(111)	(364)
Other comprehensive income (loss) before reclassifications	[1]	0	62	120	184
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	0	0	0
Other comprehensive income (loss)	[1]	0	62	120	184
Ending balance	[1]	9	(180)	9	(180)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(9,484)	(7,913)	(12,041)	(4,709)
Other comprehensive income (loss) before reclassifications	[1]	(298)	(2,750)	2,259	(5,954)
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	0	0	0
Other comprehensive income (loss)	[1]	(298)	(2,750)	2,259	(5,954)
Ending balance	[1]	(9,782)	(10,663)	(9,782)	(10,663)
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	0	126	126	126
Other comprehensive income (loss) before reclassifications	[1]	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	0	0	(126)	0
Other comprehensive income (loss)	[1]	0	0	(126)	0
Ending balance	[1]	0	126	0	126
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(7,619)	(47,130)	(8,913)	(49,648)
Other comprehensive income (loss) before reclassifications	[1]	143	473	1,547	3,161
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	(56)	(85)	(166)	(255)
Other comprehensive income (loss)	[1]	87	388	1,381	2,906
Ending balance	[1]	$ (7,532)	$ (46,742)	$ (7,532)	$ (46,742)

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