Schedule I - Condensed Financial Information of the Parent (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Other, net	$ (558)	$ (72)
Other (income) expense	1,461	3,712
Administrative and general expenses	49,192	47,491
Income tax benefit	7,378	639
Income from continuing operations	34,785	28,463
Income from discontinued operations	0	1,874
Net income	34,785	30,337
Foreign currency translation adjustment	0	1,725
Deferred gain on available for sale securities, net of tax	0	834
Current period cash flow hedging activity, net of $941 tax expense in 2017	0	1,543
Reclassification of hedging activities into earnings, net of $1,255 tax expense in 2017	0	(2,369)
Current period pension and postretirement plan adjustment, net of $14 tax benefit in 2018 and net of $440 tax expense in 2017, respectively	(301)	749
Reclassification of pension and postretirement adjustments into earnings, net of $85 and $363 tax benefit in 2018 and 2017, respectively	489	582
Total other comprehensive income	188	3,064
Comprehensive income	34,973	33,401
Current period cash flow hedging activity, tax benefit	0	941
Reclassification of hedging activities into earnings, tax benefit	0	1,255
Current period pension and postretirement plan adjustment, tax benefit	(14)	440
Reclassification of pension and post retirement adjustments into earnings, tax benefit	(85)	(363)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Intercompany interest expense	1,223	1,256
Other, net	(613)	(314)
Other (income) expense	610	942
Administrative and general expenses	5,962	6,466
Income (loss) from continuing operations before income tax provision (benefit)	(6,572)	(7,408)
Income tax benefit	(676)	(366)
Net loss before equity in earnings of subsidiaries	(5,896)	(7,042)
Equity in earnings of subsidiaries	40,681	35,505
Income from continuing operations	34,785	28,463
Income from discontinued operations	0	1,874
Net income	34,785	30,337
Foreign currency translation adjustment	0	1,725
Deferred gain on available for sale securities, net of tax	0	834
Current period cash flow hedging activity, net of $941 tax expense in 2017	0	1,543
Reclassification of hedging activities into earnings, net of $1,255 tax expense in 2017	0	(2,369)
Current period pension and postretirement plan adjustment, net of $14 tax benefit in 2018 and net of $440 tax expense in 2017, respectively	(301)	749
Reclassification of pension and postretirement adjustments into earnings, net of $85 and $363 tax benefit in 2018 and 2017, respectively	489	582
Total other comprehensive income	188	3,064
Comprehensive income	34,973	33,401
Current period cash flow hedging activity, tax benefit		941
Reclassification of hedging activities into earnings, tax benefit		1,255
Current period pension and postretirement plan adjustment, tax benefit	(14)	440
Reclassification of pension and post retirement adjustments into earnings, tax benefit	$ (85)	$ (363)