Accumulated Other Comprehensive Loss - Components of and Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income
Balance at beginning of period	$ (11,635)	$ (12,780)
Other comprehensive income before reclassifications	1,340	289
Amounts reclassified from accumulated other comprehensive loss, net of tax of $(0.1) million	154	190
Amounts reclassified from accumulated other comprehensive loss, tax	(100)	(100)
Net current period other comprehensive income, net of tax	1,494	479
Accumulated other comprehensive (loss) income	(10,141)	(12,301)
Unrecognized pension and postretirement benefits
Accumulated Other Comprehensive Income
Balance at beginning of period	(10,495)	(11,968)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss, net of tax of $(0.1) million	154	190
Net current period other comprehensive income, net of tax	154	190
Accumulated other comprehensive (loss) income	(10,341)	(11,778)
Foreign currency
Accumulated Other Comprehensive Income
Balance at beginning of period	(1,140)	(812)
Other comprehensive income before reclassifications	1,340	289
Amounts reclassified from accumulated other comprehensive loss, net of tax of $(0.1) million	0	0
Net current period other comprehensive income, net of tax	1,340	289
Accumulated other comprehensive (loss) income	$ 200	$ (523)