v2.4.1.9

Long-Term Debt Senior Notes (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended | 3 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2014 | Mar. 31, 2014 | Sep. 30, 2014 | Dec. 01, 2014 | Aug. 05, 2014 | Mar. 20, 2014
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Payments for Derivative Instrument, Investing Activities | $ 2.1 us-gaap_PaymentsForDerivativeInstrumentInvestingActivities | $ 0 us-gaap_PaymentsForDerivativeInstrumentInvestingActivities | $ 0.3 us-gaap_PaymentsForDerivativeInstrumentInvestingActivities |  |  |  |  |  |
Proceeds from issuance of long-term debt | 1,175.0 us-gaap_ProceedsFromIssuanceOfLongTermDebt | 1,535.2 us-gaap_ProceedsFromIssuanceOfLongTermDebt | 135.7 us-gaap_ProceedsFromIssuanceOfLongTermDebt |  |  |  |  |  |
Debt, long-term and short-term | 3,192.4 us-gaap_DebtInstrumentCarryingAmount |  |  | 3,192.4 us-gaap_DebtInstrumentCarryingAmount |  |  |  |  |
Deferred financing costs, net | 33.0 us-gaap_DeferredFinanceCostsNoncurrentNet | 30.1 us-gaap_DeferredFinanceCostsNoncurrentNet | 53.2 us-gaap_DeferredFinanceCostsNoncurrentNet | 33.0 us-gaap_DeferredFinanceCostsNoncurrentNet |  |  |  |  |
Gains (Losses) on Extinguishment of Debt | (90.7)us-gaap_GainsLossesOnExtinguishmentOfDebt | (64.0)us-gaap_GainsLossesOnExtinguishmentOfDebt | (17.2)us-gaap_GainsLossesOnExtinguishmentOfDebt |  |  |  |  |  |
Write off of Deferred Debt Issuance Cost | 12.6 us-gaap_WriteOffOfDeferredDebtIssuanceCost | 20.1 us-gaap_WriteOffOfDeferredDebtIssuanceCost |  |  |  |  |  |  |
Senior notes due 2019 [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Long-term debt, stated interest rate | 8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 8.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |  |
Redemption Premium, percentage of par value |  |  |  |  |  |  | 106.202%cdw_RedemptionPremiumpercentageofparvalue / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 108.764%cdw_RedemptionPremiumpercentageofparvalue / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 109.75%cdw_RedemptionPremiumpercentageofparvalue / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member
Extinguishment of Debt, Accrued Interest Paid to Lenders |  |  |  |  |  |  |  |  | 1.0 cdw_ExtinguishmentOfDebtAccruedInterestPaidToLenders / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member
Debt, long-term and short-term | 503.9 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 1,305.0 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  | 503.9 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |  |
Premium, Unamortized | 1.3 us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 4.2 us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  | 1.3 us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |  |
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
Gains (Losses) on Extinguishment of Debt | 36.9 us-gaap_GainsLossesOnExtinguishmentOfDebt / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 22.1 us-gaap_GainsLossesOnExtinguishmentOfDebt / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  | 2.7 us-gaap_GainsLossesOnExtinguishmentOfDebt / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |
Write off of Deferred Debt Issuance Cost | 4.7 us-gaap_WriteOffOfDeferredDebtIssuanceCost / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 2.2 us-gaap_WriteOffOfDeferredDebtIssuanceCost / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 0.3 us-gaap_WriteOffOfDeferredDebtIssuanceCost / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |
Extinguishment of Debt, Fees Paid to Lenders | 23.0 cdw_ExtinguishmentOfDebtFeesPaidToLenders / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 10.0 cdw_ExtinguishmentOfDebtFeesPaidToLenders / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member | 2.4 cdw_ExtinguishmentOfDebtFeesPaidToLenders / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |
Extinguishment of Debt, Make-whole Interest Payment | 10.6 cdw_ExtinguishmentofDebtMakewholeInterestPayment / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 10.6 cdw_ExtinguishmentofDebtMakewholeInterestPayment / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |  |
Write off of Deferred Debt issuance Cost, unamortized premium | 1.4 cdw_WriteoffofDeferredDebtissuanceCostunamortizedpremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  | 0.7 cdw_WriteoffofDeferredDebtissuanceCostunamortizedpremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesDue2019Member |  |  |  |  |
Senior Notes due 2022 [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Long-term debt, stated interest rate | 6.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  | 6.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  |  |  |
Debt, long-term and short-term | 600.0 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  | 600.0 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  |  |  |
Premium, Unamortized |  | 0 us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  |  |  |  |  |
Deferred financing costs, net | 8.0 us-gaap_DeferredFinanceCostsNoncurrentNet / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  | 8.0 us-gaap_DeferredFinanceCostsNoncurrentNet / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2022Member |  |  |  |  |
Senior Notes due 2024 [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Long-term debt, stated interest rate | 5.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  | 5.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  |  |  |
Debt, long-term and short-term | 575.0 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  | 575.0 us-gaap_DebtInstrumentCarryingAmount / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  |  |  |
Premium, Unamortized |  | 0 us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  |  |  |  |  |
Deferred financing costs, net | 7.5 us-gaap_DeferredFinanceCostsNoncurrentNet / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  | 7.5 us-gaap_DeferredFinanceCostsNoncurrentNet / us-gaap_LongtermDebtTypeAxis = cdw_SeniorNotesdue2024Member |  |  |  |  |
Cap agreement effective January 14, 2015-2017 [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Payments for Derivative Instrument, Investing Activities | 2.1 us-gaap_PaymentsForDerivativeInstrumentInvestingActivities / us-gaap_DerivativeByNatureAxis = cdw_CapagreementeffectiveJanuary1420152017Member |  |  |  |  |  |  |  |
Derivative Asset, Noncurrent | 1.7 us-gaap_DerivativeAssetsNoncurrent / us-gaap_DerivativeByNatureAxis = cdw_CapagreementeffectiveJanuary1420152017Member |  |  | 1.7 us-gaap_DerivativeAssetsNoncurrent / us-gaap_DerivativeByNatureAxis = cdw_CapagreementeffectiveJanuary1420152017Member |  |  |  |  |
Derivative, Notional Amount | $ 1,000.0 invest_DerivativeNotionalAmount / us-gaap_DerivativeByNatureAxis = cdw_CapagreementeffectiveJanuary1420152017Member |  |  | $ 1,000.0 invest_DerivativeNotionalAmount / us-gaap_DerivativeByNatureAxis = cdw_CapagreementeffectiveJanuary1420152017Member |  |  |  |  |

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- Definition Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or 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 20 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 + Details
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- Definition The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400 + Details
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- Definition Net amount of long-term deferred finance costs capitalized at the end of the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 17 -Article 5 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 + Details
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