CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 12,940	$ 19,154	$ 17,068	$ 39,866
Pension and other postretirement benefit plans:
Net actuarial gain (loss), net of tax of: (2016 – Three-month period $822, Nine-month period $2,637; 2015 – Three-month period $4,317, Nine-month period $3,968)	1,294	(6,780)	(4,141)	(6,232)
Pension settlement expense, net of tax of: (2016 – Three-month period $313, Nine-month period $882; 2015 – Three-month period $296, Nine-month period $964)	490	466	1,385	1,514
Amortization of unrecognized net periodic benefit costs, net of tax of: (2016 – Three-month period $496, Nine month period $1,410 ; 2015 – Three-month period $330, Nine-month period $1,126)
Net actuarial loss	807	545	2,301	1,854
Prior service credit	(29)	(29)	(87)	(87)
Interest rate swap and foreign currency translation:
Change in unrealized income (loss) on interest rate swap, net of tax of: (2016 – Three-month period $168, Nine month period $278; 2015 – Three-month period $312, Nine-month period $389)	262	(483)	(430)	(603)
Change in foreign currency translation, net of tax of: (2016 – Three-month period $127, Nine-month period $158; 2015 – Three-month period $225, Nine-month period $351)	(420)	(354)	29	(552)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	2,404	(6,635)	(943)	(4,106)
TOTAL COMPREHENSIVE INCOME	$ 15,344	$ 12,519	$ 16,125	$ 35,760