Pension Benefits - Net Periodic Pension Cost (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 29, 2016 USD ($)	Jun. 25, 2017 USD ($)	Jun. 26, 2016 USD ($)	Jun. 25, 2017 USD ($) plan	Jun. 26, 2016 USD ($)
Pension Benefits
Number of joint Company and Guild-sponsored defined benefit plans | plan				2
Multiemployer pension plan withdrawal expense	$ 5,000	$ 0	$ 11,701	$ 0	$ 11,701
Qualified Plans
Pension Benefits
Service cost		2,423	2,248	4,846	4,495
Interest cost		15,594	16,573	31,188	33,147
Expected return on plan assets		(26,136)	(27,789)	(52,272)	(55,579)
Amortization of actuarial loss		7,353	7,068	14,706	14,137
Amortization of prior service credit		(486)	(486)	(972)	(972)
Net periodic postretirement benefit income		(1,252)	(2,386)	(2,504)	(4,772)
Pension contributions				3,800	3,900
Non-Qualified Plans
Pension Benefits
Service cost		0	0	0	0
Interest cost		1,956	2,034	3,912	4,068
Expected return on plan assets		0	0	0	0
Amortization of actuarial loss		1,088	1,053	2,176	2,106
Amortization of prior service credit		0	0	0	0
Net periodic postretirement benefit income		3,044	3,087	6,088	6,174
All Plans
Pension Benefits
Service cost		2,423	2,248	4,846	4,495
Interest cost		17,550	18,607	35,100	37,215
Expected return on plan assets		(26,136)	(27,789)	(52,272)	(55,579)
Amortization of actuarial loss		8,441	8,121	16,882	16,243
Amortization of prior service credit		(486)	(486)	(972)	(972)
Net periodic postretirement benefit income		$ 1,792	$ 701	3,584	$ 1,402
Expected contributions in 2017				$ 8,000