Retirement Benefit Plans and Postretirement and Postemployment Benefit Obligations (Details) $ in Thousands	4 Months Ended		9 Months Ended
	Oct. 07, 2018 USD ($)	Oct. 08, 2017 USD ($)	Oct. 07, 2018 USD ($) employee	Oct. 08, 2017 USD ($)
Single-Employer Plan
Retirement Benefit Plans and Postretirement and Postemployment Benefit Obligations
Vesting period for plan participation			5 years
Number of employees that remain eligible for pension benefits under prior terms | employee			450
Components of net periodic benefit cost
Service cost	$ 700	$ 604	$ 1,564	$ 1,397
Interest cost	3,135	2,958	7,000	6,837
Expected return on plan assets	(3,735)	(3,117)	(8,341)	(7,204)
Amortization of net actuarial loss	67	191	149	441
Net periodic benefit cost	167	636	372	1,471
Employer contributions to the Plan			8,900
Expected total minimum required contribution	8,800		8,800
Supplemental Executive Retirement Plan
Components of net periodic benefit cost
Interest cost	308	336	771	839
Net periodic benefit cost	308	336	771	839
Postretirement health care plan
Components of net periodic benefit cost
Service cost	154	154	385	385
Interest cost	185	185	462	462
Net periodic benefit cost	$ 339	$ 339	$ 847	$ 847