v2.4.1.9

Equity Investments (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Equity Investments [Abstract] |  |  |
Equity Method Investment, Ownership Percentage | 35.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |  |
Equity Method Investment, Percentage Available to be Acquired | 65.00%cdw_EquityMethodInvestmentPercentageAvailabletobeAcquired |  |
Payments to Acquire Equity Method Investments | $ 86.8 us-gaap_PaymentsToAcquireEquityMethodInvestments | $ 0 us-gaap_PaymentsToAcquireEquityMethodInvestments | $ 0 us-gaap_PaymentsToAcquireEquityMethodInvestments
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity | $ 119.2 us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity |  |

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- Definition Equity Method Investment, Percentage Available to be Acquired + References No definition available. + Details
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- Definition Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585 + Details
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