v2.4.0.8

Long-Term Debt -Term Loan (Details) (USD $)	3 Months Ended		9 Months Ended			1 Months Ended		9 Months Ended					9 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jul. 02, 2013	Jul. 31, 2013 Term Loan [Member]	Apr. 30, 2013 Term Loan [Member]	Sep. 30, 2013 Term Loan [Member]	Sep. 30, 2014 Term Loan [Member]		Dec. 31, 2013 Term Loan [Member]	Apr. 29, 2013 Term Loan [Member]	Sep. 30, 2014 Revolving Loan [Member]		Dec. 31, 2013 Revolving Loan [Member]	Sep. 30, 2013 Prior Term Loan Facility [Member]	Apr. 29, 2013 Prior Term Loan Facility [Member]	Sep. 30, 2014 Accounts Payable, Inventory Financing [Member] Revolving Loan [Member]	Sep. 30, 2014 ABR [Member] Minimum [Member] Term Loan [Member]	Sep. 30, 2014 ABR [Member] Minimum [Member] Revolving Loan [Member]	Sep. 30, 2014 ABR [Member] Maximum [Member] Term Loan [Member]	Sep. 30, 2014 ABR [Member] Maximum [Member] Revolving Loan [Member]	Sep. 30, 2014 LIBOR [Member] Term Loan [Member]		Sep. 30, 2014 LIBOR [Member] Minimum [Member] Term Loan [Member]	Sep. 30, 2014 LIBOR [Member] Minimum [Member] Revolving Loan [Member]	Sep. 30, 2014 LIBOR [Member] Maximum [Member] Term Loan [Member]	Sep. 30, 2014 LIBOR [Member] Maximum [Member] Revolving Loan [Member]
Debt Instrument [Line Items]
Variable Interest Rate Margin																			1.25%	0.50%	1.50%	1.00%			2.25%	1.50%	2.50%	2.00%
Floorplan sub-facility, variation between balance in financials and balance per financial intermediary due to timing differences in reporting																		$ 6,300,000
Proceeds from Issuance of Long-term Debt			600,000,000	1,535,200,000			1,350,000,000
Debt, short-term and long-term									1,517,400,000		1,528,900,000		0		0		1,299,500,000
Proceeds from exercise in full of overallotment option					56,000,000
Net leverage ratio									3.2
Long-term Debt, Weighted Average Interest Rate									3.25%	[1]			0.00%	[1]									3.25%	[1]
Term Loan Repayments																40,000,000
Discount, percent of par						99.25%						99.75%
Discount, Unamortized						1,400,000			3,900,000		4,400,000	3,400,000
Variable Interest Rate, ABR Determination, Percentage Plus One-Month LIBOR													1.00%
Net loss on extinguishments of long-term debt	(45,800,000)	(41,300,000)	(53,800,000)	(55,500,000)				(10,300,000)					(400,000)
Proceeds from Issuance of Debt						190,000,000
Deferred Finance Costs, Net						$ 6,100,000							$ 6,400,000
Quarterly amortization payment of original principal, Percent									0.25%
[1] Interest rate at September 30, 2014

X

- Definition

Discount, percent of par

+ References

No definition available.

+ Details

Name:	cdw_DiscountPercentOfPar
Namespace Prefix:	cdw_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Floorplan sub-facility, variation between balance in financials and balance per financial intermediary due to timing differences in reporting

+ References

No definition available.

+ Details

Name:	cdw_FloorplanSubFacilityVariationBetweenBalanceInFinancialsAndBalancePerFinancialIntermediaryDueToTimingDifferencesInReporting
Namespace Prefix:	cdw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Net leverage ratio

+ References

No definition available.

+ Details

Name:	cdw_NetLeverageRatio
Namespace Prefix:	cdw_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Proceeds from exercise in full of overallotment option

+ References

No definition available.

+ Details

Name:	cdw_Proceedsfromexerciseinfullofoverallotmentoption
Namespace Prefix:	cdw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Quarterly amortization payment of original principal, Percent

+ References

No definition available.

+ Details

Name:	cdw_QuarterlyAmortizationPaymentOfOriginalPrincipalPercent
Namespace Prefix:	cdw_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Variable Interest Rate, ABR Determination, Percentage Plus One-Month LIBOR

+ References

No definition available.

+ Details

Name:	cdw_VariableInterestRateAbrDeterminationPercentagePlusOneMonthLibor
Namespace Prefix:	cdw_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Variable Interest Rate Margin

+ References

No definition available.

+ Details

Name:	cdw_VariableInterestRateMargin
Namespace Prefix:	cdw_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- 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

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount of debt discount 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

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ 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

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

+ Details

Name:	us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration