Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 423,860	$ 166,830	$ 55,661
Other comprehensive income (loss), net of tax:
Net gain (loss) arising during the period, net of tax expense (benefit) of $11,444, $(3,531) and $(1,348)	31,525	(10,053)	(3,836)
Effect of pension settlement, net of tax benefit of $0, $11,117, and $0		31,811
Amortization of actuarial loss included in net income, net of tax expense of $4,901, $4,445 and $3,772	11,732	12,653	10,737
Amortization of prior service credit included in net income, net of tax benefit of $(288), $(303) and $(2,244)	(818)	(860)	(6,389)
Cash flow hedges, net of tax expense (benefit) of $1,706, $396 and $(978)	35,312	(7,181)	(18,440)
Other comprehensive income (loss), net of tax	77,751	26,370	(17,928)
Comprehensive income	$ 501,611	$ 193,200	$ 37,733