v2.4.1.9

Supplemental Guarantor Information Condensed Consolidating Balance Sheets (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
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Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | $ 344.5 us-gaap_CashAndCashEquivalentsAtCarryingValue | $ 188.1 us-gaap_CashAndCashEquivalentsAtCarryingValue | $ 37.9 us-gaap_CashAndCashEquivalentsAtCarryingValue | $ 99.9 us-gaap_CashAndCashEquivalentsAtCarryingValue
Accounts receivable, net of allowance for doubtful accounts | 1,561.1 us-gaap_AccountsReceivableNetCurrent | 1,451.0 us-gaap_AccountsReceivableNetCurrent |  |
Merchandise inventory | 337.5 us-gaap_InventoryNet | 382.0 us-gaap_InventoryNet |  |
Miscellaneous receivables | 155.6 us-gaap_OtherReceivablesNetCurrent | 146.3 us-gaap_OtherReceivablesNetCurrent |  |
Prepaid expenses and other | 54.7 us-gaap_PrepaidExpenseAndOtherAssetsCurrent | 46.1 us-gaap_PrepaidExpenseAndOtherAssetsCurrent |  |
Total current assets | 2,453.4 us-gaap_AssetsCurrent | 2,213.5 us-gaap_AssetsCurrent |  |
Property and equipment, net | 137.2 us-gaap_PropertyPlantAndEquipmentNet | 131.1 us-gaap_PropertyPlantAndEquipmentNet |  |
Equity Method Investments | 86.7 us-gaap_EquityMethodInvestments | 0 us-gaap_EquityMethodInvestments |  |
Goodwill | 2,217.6 us-gaap_Goodwill | 2,220.3 us-gaap_Goodwill | 2,209.3 us-gaap_Goodwill |
Other intangible assets, net | 1,168.8 us-gaap_IntangibleAssetsNetExcludingGoodwill | 1,328.0 us-gaap_IntangibleAssetsNetExcludingGoodwill |  |
Deferred financing costs, net | 33.0 us-gaap_DeferredFinanceCostsNoncurrentNet | 30.1 us-gaap_DeferredFinanceCostsNoncurrentNet | 53.2 us-gaap_DeferredFinanceCostsNoncurrentNet |
Other assets | 3.2 us-gaap_OtherAssetsNoncurrent | 1.6 us-gaap_OtherAssetsNoncurrent |  |
Total assets | 6,099.9 us-gaap_Assets | 5,924.6 us-gaap_Assets |  |
Accounts payable-trade | 704.0 us-gaap_AccountsPayableTradeCurrent | 662.8 us-gaap_AccountsPayableTradeCurrent |  |
Accounts payable-inventory financing | 332.1 cdw_AccountsPayableInventoryFinancing | 256.6 cdw_AccountsPayableInventoryFinancing |  |
Current maturities of long-term debt | 15.4 us-gaap_LongTermDebtCurrent | 45.4 us-gaap_LongTermDebtCurrent |  |
Deferred revenue | 81.3 us-gaap_DeferredRevenueCurrent | 94.8 us-gaap_DeferredRevenueCurrent |  |
Total current liabilities | 1,468.0 us-gaap_LiabilitiesCurrent | 1,402.6 us-gaap_LiabilitiesCurrent |  |
Debt | 3,174.6 us-gaap_LongTermDebtNoncurrent | 3,205.8 us-gaap_LongTermDebtNoncurrent |  |
Deferred income taxes | 475.0 us-gaap_DeferredTaxLiabilitiesNoncurrent | 563.5 us-gaap_DeferredTaxLiabilitiesNoncurrent |  |
Other liabilities | 45.8 us-gaap_OtherLiabilitiesNoncurrent | 41.0 us-gaap_OtherLiabilitiesNoncurrent |  |
Total long-term liabilities | 3,695.4 us-gaap_LiabilitiesNoncurrent | 3,810.3 us-gaap_LiabilitiesNoncurrent |  |
Total shareholders' (deficit) equity | 936.5 us-gaap_StockholdersEquity | 711.7 us-gaap_StockholdersEquity | 136.5 us-gaap_StockholdersEquity | (7.3)us-gaap_StockholdersEquity
Total liabilities and shareholders' (deficit) equity | 6,099.9 us-gaap_LiabilitiesAndStockholdersEquity | 5,924.6 us-gaap_LiabilitiesAndStockholdersEquity |  |
Parent Guarantor [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Accounts receivable, net of allowance for doubtful accounts | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Merchandise inventory | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Miscellaneous receivables | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Prepaid expenses and other | 0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total current assets | 0 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Property and equipment, net | 0 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Equity Method Investments | 0 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |  |
Goodwill | 0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Other intangible assets, net | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Other assets | 4.3 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 4.9 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Investments in and advances to subsidiaries | 932.2 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 706.8 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total assets | 936.5 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 711.7 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Accounts payable-trade | 0 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Accounts payable-inventory financing | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Current maturities of long-term debt | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Deferred revenue | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Accrued expenses | 0 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total current liabilities | 0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Debt | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Deferred income taxes | 0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Other liabilities | 0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total long-term liabilities | 0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total shareholders' (deficit) equity | 936.5 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 711.7 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Total liabilities and shareholders' (deficit) equity | 936.5 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 711.7 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
Subsidiary Issuer [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 346.4 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 196.5 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 48.0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 102.1 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember
Accounts receivable, net of allowance for doubtful accounts | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Merchandise inventory | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Miscellaneous receivables | 56.1 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 49.9 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Prepaid expenses and other | 11.0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 10.7 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total current assets | 413.5 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 257.1 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Property and equipment, net | 80.5 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 69.7 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Equity Method Investments | 86.7 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |  |
Goodwill | 751.8 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 751.9 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Other intangible assets, net | 320.0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 338.5 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Deferred financing costs, net | 33.0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 30.1 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Other assets | 3.2 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 1.4 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Investments in and advances to subsidiaries | 2,784.5 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 2,909.4 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total assets | 4,473.2 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 4,358.1 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Accounts payable-trade | 23.9 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 21.4 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Accounts payable-inventory financing | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Current maturities of long-term debt | 15.4 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 45.4 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Deferred revenue | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Accrued expenses | 137.8 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 163.5 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total current liabilities | 177.1 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 230.3 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Debt | 3,174.6 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 3,205.8 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Deferred income taxes | 146.7 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 178.3 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Other liabilities | 42.6 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 36.9 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total long-term liabilities | 3,363.9 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 3,421.0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total shareholders' (deficit) equity | 932.2 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 706.8 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Total liabilities and shareholders' (deficit) equity | 4,473.2 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember | 4,358.1 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_SubsidiaryIssuerMember |  |
Guarantor Subsidiaries [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 15.8 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Accounts receivable, net of allowance for doubtful accounts | 1,479.1 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 1,375.9 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Merchandise inventory | 333.9 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 378.9 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Miscellaneous receivables | 93.3 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 91.0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Prepaid expenses and other | 46.0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 33.4 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total current assets | 1,952.3 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 1,879.2 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Property and equipment, net | 55.5 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 59.6 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Equity Method Investments | 0 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |  |
Goodwill | 1,439.0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 1,439.0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Other intangible assets, net | 843.6 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 982.8 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Other assets | 0.4 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0.1 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Investments in and advances to subsidiaries | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total assets | 4,290.8 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 4,360.7 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Accounts payable-trade | 671.9 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 637.3 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Accounts payable-inventory financing | 332.1 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 256.6 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Current maturities of long-term debt | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Deferred revenue | 79.9 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 89.9 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Accrued expenses | 193.6 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 175.1 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total current liabilities | 1,277.5 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 1,158.9 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Debt | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Deferred income taxes | 331.3 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 388.4 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Other liabilities | 3.7 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 3.6 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total long-term liabilities | 335.0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 392.0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total shareholders' (deficit) equity | 2,678.3 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 2,809.8 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Total liabilities and shareholders' (deficit) equity | 4,290.8 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 4,360.7 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
Non-Guarantor Subsidiaries [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 24.6 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 14.0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 9.8 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 8.1 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Accounts receivable, net of allowance for doubtful accounts | 82.0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 75.1 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Merchandise inventory | 3.6 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 3.1 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Miscellaneous receivables | 6.2 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 5.4 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Prepaid expenses and other | 1.5 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 5.1 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total current assets | 117.9 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 102.7 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Property and equipment, net | 1.2 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1.8 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Equity Method Investments | 0 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |  |
Goodwill | 26.8 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 29.4 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Other intangible assets, net | 5.2 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 6.7 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Other assets | 1.4 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0.9 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Investments in and advances to subsidiaries | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total assets | 152.5 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 141.5 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Accounts payable-trade | 34.7 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 26.5 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Accounts payable-inventory financing | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Current maturities of long-term debt | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Deferred revenue | 1.4 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 4.9 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Accrued expenses | 7.9 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 7.5 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total current liabilities | 44.0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 38.9 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Debt | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Deferred income taxes | 1.3 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1.6 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Other liabilities | 1.0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1.4 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total long-term liabilities | 2.3 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 3.0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total shareholders' (deficit) equity | 106.2 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 99.6 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Total liabilities and shareholders' (deficit) equity | 152.5 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 141.5 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
Co-Issuer [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = cdw_CoIssuerMember
Accounts receivable, net of allowance for doubtful accounts | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Merchandise inventory | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Miscellaneous receivables | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Prepaid expenses and other | 0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total current assets | 0 us-gaap_AssetsCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_AssetsCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Property and equipment, net | 0 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Equity Method Investments | 0 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = cdw_CoIssuerMember |  |  |
Goodwill | 0 us-gaap_Goodwill / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_Goodwill / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Other intangible assets, net | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Other assets | 0 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Investments in and advances to subsidiaries | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total assets | 0 us-gaap_Assets / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_Assets / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Accounts payable-trade | 0 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Accounts payable-inventory financing | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Current maturities of long-term debt | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Deferred revenue | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Accrued expenses | 0 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total current liabilities | 0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Debt | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Deferred income taxes | 0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Other liabilities | 0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total long-term liabilities | 0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total shareholders' (deficit) equity | 0 us-gaap_StockholdersEquity / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_StockholdersEquity / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Total liabilities and shareholders' (deficit) equity | 0 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = cdw_CoIssuerMember | 0 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = cdw_CoIssuerMember |  |
Consolidating Adjustments [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | (26.5)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (22.4)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (19.9)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (26.1)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Accounts receivable, net of allowance for doubtful accounts | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Merchandise inventory | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Miscellaneous receivables | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Prepaid expenses and other | (3.8)us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3.1)us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total current assets | (30.3)us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (25.5)us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Property and equipment, net |  | 0 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Equity Method Investments | 0 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |  |
Goodwill | 0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Other intangible assets, net | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Other assets | (6.1)us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (5.7)us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Investments in and advances to subsidiaries | (3,716.7)us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3,616.2)us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total assets | (3,753.1)us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3,647.4)us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Accounts payable-trade | (26.5)us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (22.4)us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Accounts payable-inventory financing | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Current maturities of long-term debt | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Deferred revenue | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Accrued expenses | (4.1)us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3.1)us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total current liabilities | (30.6)us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (25.5)us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Debt | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Deferred income taxes | (4.3)us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (4.8)us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Other liabilities | (1.5)us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (0.9)us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total long-term liabilities | (5.8)us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (5.7)us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total shareholders' (deficit) equity | (3,716.7)us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3,616.2)us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Total liabilities and shareholders' (deficit) equity | (3,753.1)us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (3,647.4)us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
Consolidated [Member] |  |  |  |
Supplemental Guarantor Information [Line Items] |  |  |  |
Cash and cash equivalents | 344.5 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 188.1 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 37.9 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 99.9 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember
Accounts receivable, net of allowance for doubtful accounts | 1,561.1 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 1,451.0 us-gaap_AccountsReceivableNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Merchandise inventory | 337.5 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 382.0 us-gaap_InventoryNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Miscellaneous receivables | 155.6 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 146.3 us-gaap_OtherReceivablesNetCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Prepaid expenses and other | 54.7 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 46.1 us-gaap_PrepaidExpenseAndOtherAssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total current assets | 2,453.4 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 2,213.5 us-gaap_AssetsCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Property and equipment, net | 137.2 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 131.1 us-gaap_PropertyPlantAndEquipmentNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Equity Method Investments | 86.7 us-gaap_EquityMethodInvestments / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |  |
Goodwill | 2,217.6 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 2,220.3 us-gaap_Goodwill / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Other intangible assets, net | 1,168.8 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 1,328.0 us-gaap_IntangibleAssetsNetExcludingGoodwill / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Deferred financing costs, net | 33.0 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 30.1 us-gaap_DeferredFinanceCostsNoncurrentNet / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Other assets | 3.2 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 1.6 us-gaap_OtherAssetsNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Investments in and advances to subsidiaries | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total assets | 6,099.9 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 5,924.6 us-gaap_Assets / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Accounts payable-trade | 704.0 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 662.8 us-gaap_AccountsPayableTradeCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Accounts payable-inventory financing | 332.1 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 256.6 cdw_AccountsPayableInventoryFinancing / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Current maturities of long-term debt | 15.4 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 45.4 us-gaap_LongTermDebtCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Deferred revenue | 81.3 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 94.8 us-gaap_DeferredRevenueCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Accrued expenses | 335.2 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 343.0 us-gaap_AccruedLiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total current liabilities | 1,468.0 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 1,402.6 us-gaap_LiabilitiesCurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Debt | 3,174.6 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 3,205.8 us-gaap_LongTermDebtNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Deferred income taxes | 475.0 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 563.5 us-gaap_DeferredTaxLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Other liabilities | 45.8 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 41.0 us-gaap_OtherLiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total long-term liabilities | 3,695.4 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 3,810.3 us-gaap_LiabilitiesNoncurrent / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total shareholders' (deficit) equity | 936.5 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | 711.7 us-gaap_StockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |
Total liabilities and shareholders' (deficit) equity | $ 6,099.9 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember | $ 5,924.6 us-gaap_LiabilitiesAndStockholdersEquity / dei_LegalEntityAxis = us-gaap_ConsolidatedEntitiesMember |  |

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 Carrying value as of the balance sheet date of obligations incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Subparagraph a -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Current Liabilities -URI http://asc.fasb.org/extlink&oid=6509677 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AccountsPayableTradeCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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