Pension and retirement plans (Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 28, 2019	Dec. 29, 2018
Components of net periodic pension costs
Service cost	$ 3,786	$ 3,734	$ 7,572	$ 7,468
Interest cost	5,638	6,614	11,276	13,228
Expected return on plan assets	(12,667)	(13,301)	(25,335)	(26,602)
Amortization of prior service cost (credit)	535	(393)	1,069	(786)
Recognized net actuarial loss	3,677	2,535	7,314	5,070
Net periodic pension cost (benefit)	969	(811)	1,896	(1,622)
Contributions			0
Selling, General and Administrative Expenses
Components of net periodic pension costs
Net periodic pension cost (benefit)	3,786	3,734	7,572	7,468
Other Income, net
Components of net periodic pension costs
Net periodic pension cost (benefit)	(2,817)	$ (4,545)	(5,676)	$ (9,090)
Plan
Components of net periodic pension costs
Estimated future employer pension plan contributions	$ 8,000		$ 8,000