Accumulated Other Comprehensive Income (Loss) - Components of and Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI, tax	$ (137)	$ (1,914,000)
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	303,503	277,451
Other comprehensive income before reclassifications	137	(387)
Amounts reclassified from accumulated other comprehensive income, net of tax of $137	349	5,772
Net current period other comprehensive income, net of tax	486	5,385
Balance at end of period	316,452	288,470
Unrecognized pension and postretirement benefits
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	360	(11,597)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income, net of tax of $137	349	5,772
Net current period other comprehensive income, net of tax	349	5,772
Balance at end of period	709	(5,825)
Foreign currency
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	220	704
Other comprehensive income before reclassifications	137	(387)
Amounts reclassified from accumulated other comprehensive income, net of tax of $137	0	0
Net current period other comprehensive income, net of tax	137	(387)
Balance at end of period	357	317
Accumulated other comprehensive income (loss)
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	580	(10,893)
Balance at end of period	$ 1,066	$ (5,508)