Pension and retirement plans (Fair Value) (Details) - USD ($) $ in Thousands	Jul. 02, 2016	Jun. 27, 2015	Jun. 28, 2014
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 516,089	$ 484,408	$ 449,960
Estimate of Fair Value Measurement
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	516,089
Estimate of Fair Value Measurement | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		484,408
Estimate of Fair Value Measurement | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	497
Estimate of Fair Value Measurement | Cash and cash equivalents | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2,111
Estimate of Fair Value Measurement | U.S. common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	204,125
Estimate of Fair Value Measurement | U.S. common stocks [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		287,495
Estimate of Fair Value Measurement | International common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102,193
Estimate of Fair Value Measurement | International common stocks [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		79,704
Estimate of Fair Value Measurement | U.S. government agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	76,991
Estimate of Fair Value Measurement | U.S. government agencies [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		8,912
Estimate of Fair Value Measurement | U.S. corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	112,262
Estimate of Fair Value Measurement | U.S. corporate bonds [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		106,186
Estimate of Fair Value Measurement | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,021
Level 1 | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	497	2,111
Level 1 | Cash and cash equivalents | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	497	2,111
Level 2 | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	515,592	482,297
Level 2 | U.S. common stocks [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	204,125	287,495
Level 2 | International common stocks [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102,193	79,704
Level 2 | U.S. government agencies [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	76,991	8,912
Level 2 | U.S. corporate bonds [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	112,262	$ 106,186
Level 2 | Other Debt Obligations [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 20,021