Pension and retirement plans (Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 02, 2021	Dec. 28, 2019	Jan. 02, 2021	Dec. 28, 2019
Components of net periodic pension costs
Service cost	$ 3,937	$ 3,786	$ 7,875	$ 7,572
Interest cost	3,976	5,638	7,952	11,276
Expected return on plan assets	(12,420)	(12,667)	(24,840)	(25,335)
Amortization of prior service cost	76	535	151	1,069
Recognized net actuarial loss	5,151	3,677	10,302	7,314
Net periodic pension cost	720	969	1,440	1,896
Selling, General and Administrative Expenses
Components of net periodic pension costs
Net periodic pension cost	3,937	3,786	7,875	7,572
Other Income, net
Components of net periodic pension costs
Net periodic pension cost	(3,217)	$ (2,817)	(6,435)	$ (5,676)
Plan
Components of net periodic pension costs
Contributions			8,000
Estimated future employer pension plan contributions	$ 8,000		$ 8,000