v2.4.1.9

Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 01, 2014 | Aug. 05, 2014 | Mar. 20, 2014
Related Party Transaction [Line Items] |  |  |  |  |  |
Management Fee | $ 0 us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | $ 2.5 us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty | $ 5.0 us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty |  |  |
Net proceeds used for termination of Management Services Agreement |  | 24.4 cdw_NetproceedsusedforterminationofManagementServicesAgreement |  |  |  |
Senior notes due 2019 [Member] |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  | $ 541.4 us-gaap_DebtInstrumentRepurchasedFaceAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | $ 234.7 us-gaap_DebtInstrumentRepurchasedFaceAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | $ 25.0 us-gaap_DebtInstrumentRepurchasedFaceAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member

X
- Definition Net proceeds used for termination of Management Services Agreement + References No definition available. + Details
Name: | cdw_NetproceedsusedforterminationofManagementServicesAgreement
Namespace Prefix: | cdw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Face (par) amount of the original debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 + Details
Name: | us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=cdw_SeniorNotesDue2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |