Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 15, 2017	Jul. 16, 2016	Jul. 15, 2017	Jul. 16, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 44,740	$ 51,155	$ 105,158	$ 110,518
Pension and postretirement plans:
Settlement loss			2,854		2,854
Net loss for the period			(36,407)		(36,407)
Amortization of prior service cost included in net income		25	17	58	50
Amortization of actuarial loss included in net income		833	646	1,943	1,666
Pension and postretirement plans, net of tax		858	(32,890)	2,001	(31,837)
Derivative instruments:
Net change in fair value of derivatives	[1]	7,238	(3,525)	3,720	(937)
Loss reclassified to net income		320	803	794	1,946
Derivative instruments, net of tax		7,558	(2,722)	4,514	1,009
Other comprehensive income (loss), net of tax		8,416	(35,612)	6,515	(30,828)
Comprehensive income		$ 53,156	$ 15,543	$ 111,673	$ 79,690

[1] Amounts in parentheses indicate debits to determine net income.