Name:	cdw_Fairvalueofoptionsissuedbyoneofthesellerstocertaincoworkersoversharesofthesellerscommonstockreceivedaspartofconsiderationfromacquisition
Namespace Prefix:	cdw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Options issued by one of the sellers to certain coworkers over shares of the seller's common stock received as part of consideration from acquisition

No definition available.

Name:	cdw_Optionsissuedbyoneofthesellerstocertaincoworkersoversharesofthesellerscommonstockreceivedaspartofconsiderationfromacquisition
Namespace Prefix:	cdw_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Share-based Compensation Arrangements by Share-based Payment Award, Awards Granted at Acquisition Date, Exercise Price

No definition available.

Name:	cdw_SharebasedCompensationArrangementsbySharebasedPaymentAwardAwardsGrantedatAcquisitionDateExercisePrice
Namespace Prefix:	cdw_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Number of shares of equity interests issued or issuable to acquire entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Name:	us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

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.