CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 44,854	$ 46,177	$ 15,811
Pension and other postretirement benefit plans:
Net gain from curtailment, net of tax of: (2013 - $11,384)			17,878
Net actuarial gain (loss), net of tax of: (2015 – $4,798; 2014 – $8,639; 2013 – $11,892)	(7,535)	(13,567)	18,683
Pension settlement expense, net of tax of: (2015 – $1,246; 2014 – $2,565; 2013 – $821)	1,956	4,030	1,290
Amortization of unrecognized net periodic benefit costs, net of tax of: (2015 – $1,571; 2014 – $979; 2013 – $3,014)
Net actuarial loss	2,585	1,652	4,847
Prior service credit	(116)	(116)	(116)
Interest rate swap and foreign currency translation:
Change in unrealized loss on interest rate swap, net of tax of: (2015 – $126; 2014 – $226)	(195)	(350)
Change in foreign currency translation, net of tax of: (2015 – $451; 2014 – $137; 2013 – $79)	(712)	(216)	(122)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	(4,017)	(8,567)	42,460
TOTAL COMPREHENSIVE INCOME	$ 40,837	$ 37,610	$ 58,271