Income taxes (Details) - USD ($) $ in Millions	3 Months Ended
Sep. 23, 2016	Sep. 25, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 0	$ 0

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Name:	us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration