Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	4 Months Ended
Apr. 18, 2020	Apr. 20, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (5,772)	$ 65,866
Pension and postretirement plans:
Settlement and curtailment loss	86,865
Net gain for the period	15,693
Amortization of prior service cost included in net income	55	79
Amortization of actuarial loss included in net income	953	1,569
Pension and postretirement plans, net of tax	103,566	1,648
Derivative instruments:
Net change in fair value of derivatives	(3,849)	(9,593)
Loss (gain) reclassified to net income	411	(2,178)
Derivative instruments, net of tax	(3,438)	(11,771)
Other comprehensive income (loss), net of tax	100,128	(10,123)
Comprehensive income	$ 94,356	$ 55,743

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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