Name:	gww_GoodwillImpairmentLossExcludingDivestedBusinesses
Namespace Prefix:	gww_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Reporting Unit, Change In Percentage of Fair Value in Excess of Carrying Amount

No definition available.

Name:	gww_ReportingUnitChangeInPercentageOfFairValueInExcessOfCarryingAmount
Namespace Prefix:	gww_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Reporting Unit, Impairment Trigger, Decrease In Revenue Long-Term Growth Rate

No definition available.

Name:	gww_ReportingUnitImpairmentTriggerDecreaseInRevenueLongTermGrowthRate
Namespace Prefix:	gww_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Reporting Unit, Impairment Trigger, Pre-Tax Discount Rate

No definition available.

Name:	gww_ReportingUnitImpairmentTriggerPreTaxDiscountRate
Namespace Prefix:	gww_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

No definition available.

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

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13854-109267

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266

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

Percentage of fair value of reporting unit in excess of carrying amount.

No definition available.

Name:	us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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.

No definition available.

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

Name:	srt_StatementGeographicalAxis=country_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=srt_ProFormaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementBusinessSegmentsAxis=country_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: