Loss Contingency, Data Breach, Number of Incidents

No definition available.

Name:	aci_LossContingencyDataBreachNumberOfIncidents
Namespace Prefix:	aci_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Number of claims dismissed.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of stores.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Commitments and Contingencies and Off Balance Sheet Arrangements - Legal Contingencies (Details) $ in Millions		9 Months Ended	12 Months Ended
	Aug. 29, 2018 claim	Dec. 01, 2018 USD ($) claim lawsuit	Jan. 03, 2015 claim store	Oct. 06, 2015 incident
Security breach
Loss Contingencies [Line Items]
Number of stores \| store			800
Number of claims filed and dismissed			2
Consolidated cases for multidistrict litigation
Loss Contingencies [Line Items]
Number of lawsuits filed against the company		62
Pending litigation \| Qui Tam Lawsuits
Loss Contingencies [Line Items]
Number of lawsuits filed against the company \| lawsuit		2
Pending litigation \| Qui Tam Lawsuits \| Minimum
Loss Contingencies [Line Items]
Loss contingency, amount of damages sought \| $		$ 100
Pending litigation \| Safeway Inc \| Safeway's 401(k) Plan
Loss Contingencies [Line Items]
Number of lawsuits filed against the company \| lawsuit		2
Threatened litigation \| Security breach
Loss Contingencies [Line Items]
Number of data breach incidents \| incident				2
Threatened litigation \| Consolidated cases for multidistrict litigation \| Blackfeet Tribe
Loss Contingencies [Line Items]
New claim filed	1