Pension and retirement plans (Pension Plans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 30, 2012
Changes in benefit obligations:
Service cost	$ 36,733	$ 36,920	$ 28,380
Interest cost	17,155	14,653	14,925
Change in plan assets:
Contributions	40,000
Amounts recognized in accumulated other comprehensive income:
Unrecognized net actuarial loss	158,100
Unamortized prior service credit	(6,100)
Pension Plans [Member]
Changes in benefit obligations:
Benefit obligations at beginning of year	391,880	375,156
Service cost	36,733	36,920
Interest cost	17,155	14,653
Actuarial (gain) loss	34,726	(13,545)
Benefits paid	(23,327)	(21,304)
Benefit obligations at end of year	457,167	391,880
Change in plan assets:
Fair value of plan assets at beginning of year	365,373	301,449
Actual return on plan assets	67,914	45,228
Benefits paid	(23,327)	(21,304)
Contributions	40,000	40,000
Fair value of plan assets at end of year	449,960	365,373
Funded status of the plan recognized as a non-current asset (liability)	(7,207)	(26,507)
Amounts recognized in accumulated other comprehensive income:
Unrecognized net actuarial loss	158,103	173,069
Unamortized prior service credit	(6,050)	(7,623)
Amount recognized in accumulated other comprehensive income	152,053	165,446
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net actuarial (gain) loss	(2,280)	(30,870)
Amortization of net actuarial loss	(12,686)	(14,898)
Amortization of prior service credit	1,573	1,573
Other changes in plan assets and benefit obligations recognized in other comprehensive income	$ (13,393)	$ (44,195)
Weighted average assumptions used to calculate actuarial present values of benefit obligations
Discount rate	4.00%	4.50%
Weighted average assumptions used to determine net benefit costs
Discount rate	4.50%	4.00%
Expected return on plan assets	8.50%	8.50%