Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net earnings (loss)		$ (122,250)	$ (24,410)	$ 284,613
Other comprehensive income (loss):
Changes in cumulative translation adjustment and unrealized loss from cash flow hedges		6,867	30,681	(55,940)
Amortization of pension and postretirement items	[1]	40,362	30,305	27,499
Income tax expense related to amortization of pension and postretirement items		(9,090)	(7,059)	(6,422)
Amortization of pension and postretirement items, net of tax		31,272	23,246	21,077
Reclassification of net actuarial loss due to pension settlement		0	34,974	0
Change in net actuarial loss and prior service cost		(16,894)	(7,609)	(83,695)
Income tax benefit (expense) related to pension settlement and change in net actuarial loss and prior service cost		(1,959)	(6,149)	18,327
Change in net actuarial loss and prior service cost, net of taxes		(18,853)	21,216	(65,368)
Other comprehensive income (loss), net of taxes		19,286	75,143	(100,231)
Comprehensive income (loss)		$ (102,964)	$ 50,733	$ 184,382

[1] These amounts are included in the computation of net pension expense. Amortization in 2020 includes the curtailment loss. Refer to Note 18, "Employee Benefit Plans," for additional information.