Pension and retirement plans (Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 29, 2018	Dec. 30, 2017
Components of net periodic pension costs
Service cost	$ 3,734	$ 3,867	$ 7,468	$ 7,735
Interest cost	6,614	5,783	13,228	11,566
Expected return on plan assets	(13,301)	(13,757)	(26,602)	(27,514)
Amortization of prior service credits	(393)	(393)	(786)	(786)
Recognized net actuarial loss	2,535	3,746	5,070	7,492
Net periodic pension (benefit) cost	(811)	(754)	(1,622)	(1,507)
Selling, General and Administrative Expenses
Components of net periodic pension costs
Net periodic pension (benefit) cost	3,734	3,867	7,468	7,735
Other Income (Expense), net
Components of net periodic pension costs
Net periodic pension (benefit) cost	(4,545)	(4,621)	(9,090)	$ (9,242)
Plan
Components of net periodic pension costs
Pension settlement charge		$ 14,000
Contributions			8,000
Estimated future employer pension plan contributions	$ 8,000		$ 8,000