CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 24,376	$ 1,233	$ 29,264	$ 11,187
Pension and other postretirement benefit plans:
Net actuarial loss, net of tax of: (2019 - Three-month period $20, Six-month period $210; 2018 - Three-month period $450, Six-month period $1,349)	(58)	1,300	603	3,890
Pension settlement expense, net of tax of: (2019 - Three-month period $72, Six-month period $421; 2018 - Three-month period $111, Six-month period $279)	206	320	1,213	806
Amortization of unrecognized net periodic benefit costs, net of tax of: (2019 - Three-month period $77, Six-month period $177; 2018 - Three-month period $171, Six-month period $390)
Net actuarial loss	229	511	524	1,160
Prior service credit	(6)	(18)	(12)	(35)
Interest rate swap and foreign currency translation:
Change in unrealized income (loss) on interest rate swap, net of tax of: (2019 - Three-month period $187, Six-month period $305)	(528)		(860)
Change in unrealized income (loss) on interest rate swap, net of tax of: (2018 - Three-month period $7, Six-month period $275)		343		779
Change in foreign currency translation, net of tax of: (2019 - Three-month period $41, Six-month period $120; 2018 - Three-month period $78, Six-month period $103)	116	(220)	341	(292)
OTHER COMPREHENSIVE INCOME, net of tax	(41)	2,236	1,809	6,308
TOTAL COMPREHENSIVE INCOME	$ 24,335	$ 3,469	$ 31,073	$ 17,495