Pension and retirement plans (Periodic Pension Cost) (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Jun. 27, 2015	Jun. 28, 2014	Jun. 29, 2013
Components of net periodic pension costs
Service cost	$ 39,492	$ 36,733	$ 36,920
Interest cost	17,797	17,155	14,653
Expected return on plan assets	(36,221)	(30,908)	(27,905)
Recognized net actuarial loss	13,007	12,686	14,898
Amortization of prior service credit	(1,573)	(1,573)	(1,573)
Net periodic pension cost	$ 32,502	$ 34,093	$ 36,993