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

Loss Contingency, Multi-State Group Investigation, Number of States

+ References

No definition available.

+ Details

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

- Definition

Number Of Insurance Carriers Denied Insurance Coverage

+ References

No definition available.

+ Details

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

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementExpense
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=115931803&loc=d3e12021-110248

+ Details

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

- Definition

Number of plaintiffs that have filed claims pertaining to a loss contingency.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyNumberOfPlaintiffs
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

- Details

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Namespace Prefix:
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Balance Type:
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- Details

Name:	srt_LitigationCaseAxis=aci_MasterCardLitigationMember
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Data Type:	na
Balance Type:
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- Details

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Balance Type:
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- Details

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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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Data Type:	na
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- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_ThreatenedLitigationMember
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Data Type:	na
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- Details

Name:	dei_LegalEntityAxis=aci_ABAcquisitionMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_LitigationCaseAxis=aci_SecurityBreachMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=aci_AdditionalAssessmentsandCardReissuanceCostsMember
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Commitments and Contingencies and Off Balance Sheet Arrangements - Legal Contingencies (Details) $ in Millions	Aug. 30, 2017 plaintiff	Dec. 09, 2016 USD ($)	Aug. 10, 2015 plaintiff	Sep. 08, 2018 lawsuit	Jan. 02, 2018 USD ($)	Oct. 06, 2015 insurance_carrier incident state
Settled titigation \| MasterCard litigation
Loss Contingencies [Line Items]
Settlement payment \| $		$ 6.0
Pending litigation \| Mertz v. SuperValu Inc and Rocke V. SuperValu Inc.
Loss Contingencies [Line Items]
Number of lawsuits filed against the company				2
Number of plaintiffs \| plaintiff	1		16
Pending litigation \| Qui Tam Lawsuits
Loss Contingencies [Line Items]
Number of lawsuits filed against the company				3
Pending litigation \| Safeway Inc \| Safeway's 401(k) Plan
Loss Contingencies [Line Items]
Number of lawsuits filed against the company				2
Dismissed \| Mertz v. SuperValu Inc and Rocke V. SuperValu Inc.
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff	15
Threatened litigation \| AB Acquisition \| Security breach
Loss Contingencies [Line Items]
Number of states requesting information concerning data breach incidents \| state						14
Number of data breach incidents \| incident						2
Number of insurance carriers denied cyber insurance coverage \| insurance_carrier						2
Additional assessments and card reissuance costs \| MasterCard litigation
Loss Contingencies [Line Items]
Estimate of possible loss \| $					$ 1.0