XML 96 R81.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Coworker Retirement and Other Compensation Benefits - Coworker Stock Purchase Plan (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Coworker Retirement and Other Compensation Benefits [Line Items] |  |  |
Equity-based compensation expense | $ 40,700,000 | $ 43,700,000 | $ 39,200,000
Coworker Stock Purchase Plan |  |  |
Coworker Retirement and Other Compensation Benefits [Line Items] |  |  |
Employee stock purchase plan discount to market price (as percent) | 5.00% |  |
Equity-based compensation expense | $ 0 |  |

X
- Definition [Line Items] for Coworker Retirement and Other Compensation Benefits [Table] + References No definition available. + Details
Name: | cdw_CoworkerRetirementandOtherCompensationBenefitsLineItems
Namespace Prefix: | cdw_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Employee Stock Purchase Plan, discount to market price, percent + References No definition available. + Details
Name: | cdw_EmployeeStockPurchasePlandiscounttomarketpricepercent
Namespace Prefix: | cdw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_PlanNameAxis=cdw_CoworkerStockPurchasePlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |