CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 16,270	$ 40,776	$ 45,534	$ 51,963
Pension and other postretirement benefit plans:
Net actuarial loss, net of tax of: (2019 - Three-month period $310, Nine-month period $100; 2018 - Three-month period $2,038, Nine-month period $689)	(894)	(5,877)	(291)	(1,987)
Pension settlement expense, including termination expense, net of tax of: (2019 - Three-month period $651, Nine-month period $1,072; 2018 - Three-month period $134, Nine-month period $413)	5,850	384	7,063	1,190
Amortization of unrecognized net periodic benefit costs, net of tax of: (2019 - Three-month period $75, Nine-month period $252; 2018 - Three-month period $146, Nine-month period $536)
Net actuarial loss	222	438	746	1,598
Prior service credit	(6)	(17)	(18)	(52)
Interest rate swap and foreign currency translation:
Change in unrealized income (loss) on interest rate swap, net of tax of: (2019 - Three-month period $120, Nine-month period $425)	(338)		(1,198)
Change in unrealized income (loss) on interest rate swap, net of tax of: (2018 - Three-month period $59, Nine-month period $334)		167		946
Change in foreign currency translation, net of tax of: (2019 - Three-month period $12, Nine-month period $108; 2018 - Three-month period $45, Nine-month period $58)	(35)	127	306	(165)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	4,799	(4,778)	6,608	1,530
TOTAL COMPREHENSIVE INCOME	$ 21,069	$ 35,998	$ 52,142	$ 53,493