v2.4.1.9

Inventory Financing Agreements (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | ---
Inventory Financing Agreements [Line Items] |  |
Accounts Payable Inventory Financing | $ 332.1 cdw_AccountsPayableInventoryFinancing | $ 256.6 cdw_AccountsPayableInventoryFinancing
Accounts Payable, Inventory Financing [Member] |  |
Inventory Financing Agreements [Line Items] |  |
Revolving Loan financing agreement | 330.1 cdw_RevolvingLoanFinancingAgreement / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember | 256.1 cdw_RevolvingLoanFinancingAgreement / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember
Other inventory financing agreements | 2.0 cdw_OtherInventoryFinancingAgreements / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember | 0.5 cdw_OtherInventoryFinancingAgreements / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember
Accounts Payable Inventory Financing | 332.1 cdw_AccountsPayableInventoryFinancing / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember | 256.6 cdw_AccountsPayableInventoryFinancing / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember
Previous Revolving Credit Facility [Member] | Accounts Payable, Inventory Financing [Member] |  |
Inventory Financing Agreements [Line Items] |  |
Floorplan sub-facility | $ 400.0 cdw_FloorplanSubFacility / cdw_InventoryFinancingAgreementsAxis = cdw_AccountsPayableInventoryFinancingMember / us-gaap_LongtermDebtTypeAxis = cdw_PreviousRevolvingCreditFacilityMember |

X
- Definition Accounts payable inventory financing. + References No definition available. + Details
Name: | cdw_AccountsPayableInventoryFinancing
Namespace Prefix: | cdw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Floorplan sub-facility + References No definition available. + Details
Name: | cdw_FloorplanSubFacility
Namespace Prefix: | cdw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | cdw_InventoryFinancingAgreementsLineItems
Namespace Prefix: | cdw_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other inventory financing agreements + References No definition available. + Details
Name: | cdw_OtherInventoryFinancingAgreements
Namespace Prefix: | cdw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Revolving Loan financing agreement + References No definition available. + Details
Name: | cdw_RevolvingLoanFinancingAgreement
Namespace Prefix: | cdw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | cdw_InventoryFinancingAgreementsAxis=cdw_AccountsPayableInventoryFinancingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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