Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in accumulated other comprehensive income [Roll Forward]
Balance			$ 391,979
Other comprehensive income before reclassifications	$ (188)		(156)
Amounts reclassified from accumulated other comprehensive income	105		316
Total other comprehensive income (loss), net of tax	(83)	$ (1,869)	160	$ (3,203)
Balance	438,539		438,539
AOCI Attributable to Parent [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance	(6,231)		(6,474)
Total other comprehensive income (loss), net of tax			160
Balance	(6,314)		(6,314)
Foreign Currency Translation Adjustments [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance	(6,111)		(5,958)
Other comprehensive income before reclassifications	(188)		(341)
Amounts reclassified from accumulated other comprehensive income	0		0
Total other comprehensive income (loss), net of tax	(188)		(341)
Balance	(6,299)		(6,299)
Unrecognized Postretirement Benefit Costs (Credit) [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance	(120)		(516)
Other comprehensive income before reclassifications	0		185
Amounts reclassified from accumulated other comprehensive income	105		316
Total other comprehensive income (loss), net of tax	105		501
Balance	$ (15)		$ (15)