CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
NET INCOME	$ 213,521	$ 71,100	$ 39,985
Postretirement benefit plans:
Net actuarial gain, net of tax of: (2021 - $451; 2020 - $513, 2019 - $2,308)	1,300	1,480	6,657
Pension settlement expense, including termination expense, net of tax of: (2021 - $-; 2020 - $23, 2019 - $1,167)		66	7,338
Amortization of unrecognized net periodic benefit cost (credit), net of tax of: (2021 - $139; 2020 - $152, 2019 - $314)
Net actuarial (gain) loss	(400)	(437)	931
Prior service credit		(1)	(25)
Interest rate swap and foreign currency translation:
Change in unrealized income (loss) on interest rate swap, net of tax of: (2021 - $534; 2020 - $277, 2019 - $357)	1,507	(782)	(1,007)
Change in foreign currency translation, net of tax of: (2021 - $36; 2020 - $232, 2019 - $194)	102	661	547
OTHER COMPREHENSIVE INCOME, net of tax	2,509	987	14,441
TOTAL COMPREHENSIVE INCOME	$ 216,030	$ 72,087	$ 54,426