Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands		4 Months Ended
		Apr. 22, 2017	Apr. 23, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 60,418	$ 59,363
Pension and postretirement plans:
Amortization of prior service cost included in net income		33	33
Amortization of actuarial loss included in net income		1,110	1,020
Pension and postretirement plans, net of tax		1,143	1,053
Derivative instruments:
Net change in fair value of derivatives	[1]	(3,518)	2,588
Loss reclassified to net income		474	1,143
Derivative instruments, net of tax		(3,044)	3,731
Other comprehensive income (loss), net of tax		(1,901)	4,784
Comprehensive income		$ 58,517	$ 64,147

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