XML 38 R26.htm IDEA: XBRL DOCUMENT
v3.20.2

Description of Business and Summary of Significant Accounting Policies (Details) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 USD ($) subsidiary | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) subsidiary | Sep. 30, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |
Number of owned subsidiaries | subsidiary | 2 |  | 2 |
Advertising costs | $ 47.0 | $ 51.0 | $ 140.0 | $ 143.0
Provision for credit losses |  |  | 30.4 | $ 2.1
COVID- 19 [Member] |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |
Provision for credit losses |  |  | $ 30.0 |

X
- Definition Number of Owned Subsidiaries + References No definition available. + Details
Name: | cdw_NumberofOwnedSubsidiaries
Namespace Prefix: | cdw_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 720 -SubTopic 35 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848 + Details
Name: | us-gaap_AdvertisingExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of expense (reversal of expense) for expected credit loss on accounts receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(5)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_ProvisionForDoubtfulAccounts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_UnusualOrInfrequentItemAxis=cdw_COVID19Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |