v2.4.1.9

Segment Information Segment Reporting, by Products and Services (Details) (USD $) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales to customers outside of the US, Percent |  |  |  |  |  |  |  |  | 4.00%cdw_NetSalesToCustomersOutsideOfUsPercent |  | 4.00%cdw_NetSalesToCustomersOutsideOfUsPercent |  | 4.00%cdw_NetSalesToCustomersOutsideOfUsPercent |
Revenue, Net | $ 3,050,100,000 us-gaap_SalesRevenueNet | $ 3,266,100,000 us-gaap_SalesRevenueNet | $ 3,106,000,000 us-gaap_SalesRevenueNet | $ 2,652,300,000 us-gaap_SalesRevenueNet | $ 2,713,300,000 us-gaap_SalesRevenueNet | $ 2,864,300,000 us-gaap_SalesRevenueNet | $ 2,779,300,000 us-gaap_SalesRevenueNet | $ 2,411,700,000 us-gaap_SalesRevenueNet | $ 12,074,500,000 us-gaap_SalesRevenueNet |  | $ 10,768,600,000 us-gaap_SalesRevenueNet |  | $ 10,128,200,000 us-gaap_SalesRevenueNet |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 100.00%cdw_RevenuenetbyProductandServicePercentage |  | 100.00%cdw_RevenuenetbyProductandServicePercentage |  | 100.00%cdw_RevenuenetbyProductandServicePercentage |
Long-Lived Assets in Foreign Countries, Percent | 1.00%cdw_LongLivedAssetsInForeignCountriesPercent |  |  |  | 1.00%cdw_LongLivedAssetsInForeignCountriesPercent |  |  |  | 1.00%cdw_LongLivedAssetsInForeignCountriesPercent |  | 1.00%cdw_LongLivedAssetsInForeignCountriesPercent |  |  |
Notebooks/Mobile Devices [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 2,352,300,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |  | 1,698,400,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |  | 1,462,800,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 19.50%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |  | 15.80%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |  | 14.40%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NotebooksMobileDevicesMember |
NetComm Products [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 1,615,900,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |  | 1,486,300,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |  | 1,351,500,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 13.40%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |  | 13.80%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |  | 13.30%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_NetcommProductsMember |
Enterprise and Data Storage (Including Drives) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 1,024,300,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |  | 999,200,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |  | 981,500,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 8.50%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |  | 9.30%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |  | 9.70%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_EnterpriseAndDataStorageIncludingDrivesMember |
Other Hardware [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 4,549,200,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |  | 4,178,500,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |  | 4,075,700,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 37.60%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |  | 38.80%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |  | 40.30%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherHardwareMember |
Software [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 2,076,700,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |  | 1,993,100,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |  | 1,877,700,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 17.20%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |  | 18.50%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |  | 18.50%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_SoftwareProductsMember |
Services [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 371,400,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |  | 332,700,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |  | 285,000,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 3.10%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |  | 3.10%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |  | 2.80%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_ServicesMember |
Other [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | 84,700,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1] | 80,400,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1] | 94,000,000 us-gaap_SalesRevenueNet / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1]
Revenue net, by Product and Service, Percentage |  |  |  |  |  |  |  |  | 0.70%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1] | 0.70%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1] | 1.00%cdw_RevenuenetbyProductandServicePercentage / us-gaap_ProductOrServiceAxis = cdw_OtherProductsAndServicesMember | [1]
Public [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net | 1,169,100,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 1,468,800,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 1,271,600,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 969,900,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 990,500,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 1,244,600,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 1,082,600,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember | 846,800,000 us-gaap_SalesRevenueNet / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember |  |  |  |  |  |
Federal [Member] | Public [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net Sales from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue, Net |  |  |  |  |  |  |  |  | $ 884,200,000 us-gaap_SalesRevenueNet / cdw_PublicAxis = cdw_FederalMember / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember |  | $ 764,400,000 us-gaap_SalesRevenueNet / cdw_PublicAxis = cdw_FederalMember / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember |  | $ 964,700,000 us-gaap_SalesRevenueNet / cdw_PublicAxis = cdw_FederalMember / us-gaap_StatementBusinessSegmentsAxis = cdw_PublicMember |
[1] | Includes items such as delivery charges to customers and certain commission revenue.

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