Pension and retirement plans (Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 28, 2020	Mar. 30, 2019
Components of net periodic pension costs
Service cost	$ 3,786	$ 3,582	$ 11,358	$ 11,050
Interest cost	5,638	8,010	16,914	21,238
Expected return on plan assets	(12,668)	(16,003)	(38,003)	(42,605)
Amortization of prior service cost (credit)	534	(392)	1,603	(1,178)
Recognized net actuarial loss	3,658	2,091	10,972	7,161
Net periodic pension cost (benefit)	948	(2,712)	2,844	(4,334)
Selling, General and Administrative Expenses
Components of net periodic pension costs
Net periodic pension cost (benefit)	3,786	3,582	11,358	11,050
Other Income, net
Components of net periodic pension costs
Net periodic pension cost (benefit)	(2,838)	$ (6,294)	(8,514)	$ (15,384)
Plan
Components of net periodic pension costs
Contributions			4,000
Estimated future employer pension plan contributions	$ 4,000		$ 4,000