Pension and retirement plans (Periodic Pension Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jul. 01, 2017	Jun. 27, 2020
Components of net periodic pension costs
Service cost	$ 14,631	$ 15,834	$ 29,623
Interest cost	26,354	23,732	19,323
Expected return on plan assets	(53,518)	(54,686)	(49,279)
Amortization of prior service credits	(1,571)	(1,573)	(1,573)
Recognized net actuarial loss	9,251	14,404	14,440
Curtailment recognition of prior service credit			(614)
Net periodic pension (benefit) cost	(4,853)	(2,289)	11,920
Contributions	8,000	16,000
Selling, General and Administrative Expenses
Components of net periodic pension costs
Net periodic pension (benefit) cost	14,631	15,834	29,623
Other Income, net
Components of net periodic pension costs
Net periodic pension (benefit) cost	$ (19,484)	$ (18,123)	$ (17,703)
Forecast
Components of net periodic pension costs
Estimated future employer pension plan contributions				$ 16,000