XML 61 R49.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Supplementary Balance Sheet Information (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 29, 2018 | Sep. 30, 2017 | Sep. 24, 2016
Supplementary Balance Sheet Information [Abstract] |  |  |
Employee insurance expense | $ 37.7 | $ 33.1 | $ 34.5

X
- References No definition available. + Details
Name: | imkta_SupplementaryBalanceSheetInformationAbstract
Namespace Prefix: | imkta_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The expense in the period incurred with respect to protection provided by insurance entities against risks other than risks associated with production (which are allocated to cost of sales). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_GeneralInsuranceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration