CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME (LOSS)	$ 9,954	$ (7,407)
Pension and other postretirement benefit plans:
Net actuarial gain (loss), net of tax of: (2018 – $899; 2017 – $935)	2,590	(1,471)
Pension settlement expense, net of tax of: (2018 – $168; 2017 – $761)	486	1,196
Amortization of unrecognized net periodic benefit costs, net of tax of: (2018 – $219; 2017 – $401)
Net actuarial loss	649	660
Prior service credit	(17)	(29)
Interest rate swap and foreign currency translation:
Change in unrealized income on interest rate swap, net of tax of: (2018 – $219; 2017 – $88)	436	135
Change in foreign currency translation, net of tax of: (2018 – $223; 2017 – $76)	(72)	119
OTHER COMPREHENSIVE INCOME, net of tax	4,072	610
TOTAL COMPREHENSIVE INCOME (LOSS)	$ 14,026	$ (6,797)