Pension and retirement plans (Tables)

6 Months Ended

Dec. 31, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of net periodic pension costs

	Second Quarters Ended				Six Months Ended
	December 31,		January 2,		December 31,		January 2,
	2016		2016		2016		2016
	(Thousands)
Service cost	$	10,848	$	9,935	$	21,696	$	20,421
Interest cost		3,774		5,328		7,548		10,656
Expected return on plan assets		(10,588)		(10,071)		(21,176)		(20,142)
Recognized net actuarial loss		3,851		3,183		7,702		6,366
Amortization of prior service credits		(393)		(393)		(786)		(786)
Net periodic pension cost	$	7,492	$	7,982	$	14,984	$	16,515