Comprehensive Income (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
Net loss	$ (2,653)	$ (4,263)	$ (10,039)	$ (9,866)
Other comprehensive loss:
Adjustment to pension liability	688	596	1,252	1,466
Tax expense	(275)	(239)	(501)	(586)
Adjustment to pension liability, net of tax	(413)	(357)	(751)	(880)
Foreign currency translation adjustment	599	(949)	644	(1,419)
Total other comprehensive income (loss), net of tax	1,012	(592)	1,395	(539)
Comprehensive loss	(1,641)	(4,855)	(8,644)	(10,405)
Changes in other comprehensive loss by component
Balance at beginning of period			2,656	140,316
Total other comprehensive income (loss), net of tax	1,012	(592)	1,395	(539)
Balance at end of period	(5,030)	125,118	(5,030)	125,118
Defined Benefit Pension Items
Other comprehensive loss:
Total other comprehensive income (loss), net of tax			751	880
Changes in other comprehensive loss by component
Balance at beginning of period			(46,977)	(43,915)
Other comprehensive income (loss), net of tax, before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			751	880
Total other comprehensive income (loss), net of tax			751	880
Balance at end of period	(46,226)	(43,035)	(46,226)	(43,035)
Foreign Currency Items
Other comprehensive loss:
Total other comprehensive income (loss), net of tax			644	(1,419)
Changes in other comprehensive loss by component
Balance at beginning of period			799	355
Other comprehensive income (loss), net of tax, before reclassifications			644	(1,419)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			0	0
Total other comprehensive income (loss), net of tax			644	(1,419)
Balance at end of period	1,443	(1,064)	1,443	(1,064)
Accumulated Other Comprehensive Income (Loss)
Other comprehensive loss:
Total other comprehensive income (loss), net of tax			1,395	(539)
Changes in other comprehensive loss by component
Balance at beginning of period			(46,178)	(43,560)
Other comprehensive income (loss), net of tax, before reclassifications			644	(1,419)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			751	880
Total other comprehensive income (loss), net of tax			1,395	(539)
Balance at end of period	$ (44,783)	$ (44,099)	$ (44,783)	$ (44,099)