CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 1,233	$ 15,777	$ 11,187	$ 8,370
Pension and other postretirement benefit plans:
Net actuarial gain (loss), net of tax of: (2018 – Three-month period $450, Six-month period $1,349; 2017 – Three-month period $64, Six-month period $999)	1,300	(98)	3,890	(1,569)
Pension settlement expense, net of tax of: (2018 – Three-month period $111, Six-month period $279; 2017 – Three-month period $290, Six-month period $1,051)	320	454	806	1,650
Amortization of unrecognized net periodic benefit costs, net of tax of: (2018 – Three-month period $171, Six-month period $390; 2017 – Three-month period $352, Six-month period $753)
Net actuarial loss	511	581	1,160	1,241
Prior service credit	(18)	(29)	(35)	(58)
Interest rate swap and foreign currency translation:
Change in unrealized income on interest rate swap, net of tax of: (2018 – Three-month period $7, Six-month period $275; 2017 – Three-month period $52, Six-month period $140)	343	81	779	216
Change in foreign currency translation, net of tax of: (2018 – Three-month period $78, Six month-period $103; 2017 – Three-month period $134, Six-month period $58)	(220)	(208)	(292)	(89)
OTHER COMPREHENSIVE INCOME, net of tax	2,236	781	6,308	1,391
TOTAL COMPREHENSIVE INCOME	$ 3,469	$ 16,558	$ 17,495	$ 9,761