Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 9,200	$ 8,398	$ 23,769	$ 20,164
Foreign currency translation adjustment	0	(18)	0	1,725
Deferred gain on equity securities	0	78	0	542
Current period cash flow hedging activity, net of $1,310 and $941 tax expense in the three and nine months ended September 30, 2017, respectively.	0	2,402	0	1,543
Reclassification of hedging activities into earnings, net of $1,344 and $1,255 tax expense in the three and nine months ended September 30, 2017, respectively.	0	(2,509)	0	(2,369)
Reclassification of pension and postretirement adjustments into earnings, net of $25 and $86 tax benefit in the three and nine months ended September 30, 2018, respectively, net of $38 and $228 tax benefit in the three and nine months ended September 30, 2017, respectively.	103	191	348	515
Total other comprehensive income	103	144	348	1,956
Comprehensive income	$ 9,303	$ 8,542	$ 24,117	$ 22,120