CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ (106,693)	$ 37,302	$ (19,931)
Pension and post-retirement obligations:
Change in net actuarial loss and prior service cost, net of tax of $11,903, $(9,710) and $(5,875)	33,344	(27,007)	(16,738)
Amortization of actuarial loss (gain) and prior service cost (credit) to earnings, net of tax of $1,950, $140 and $2,842	5,444	436	7,936
Derivative instruments designated as cash flow hedges:
Change in fair value of derivatives, net of tax of $306, $(4,797) and $(6,776)	868	(13,601)	(19,237)
Cumulative adjustment upon adoption of ASU 2017-12, net of tax of $(203)			(576)
Reclassification of realized loss to earnings, net of tax of $3,773, $4,061 and $149	10,191	11,622	959
Comprehensive income (loss)	(56,846)	8,752	(47,587)
Less: comprehensive income attributable to noncontrolling interest	392	325	452
Total comprehensive income (loss) attributable to common shareholders	$ (57,238)	$ 8,427	$ (48,039)