Subsequent Events (Notes)	6 Months Ended
Jun. 30, 2013
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On July 2, 2013, the Company completed an IPO of 23,250,000 shares of common stock. On July 31, 2013, the Company completed the sale of an additional 3,487,500 shares of common stock to the underwriters of the IPO pursuant to the underwriters' July 26, 2013 exercise in full of the overallotment option granted to them in connection with the IPO. Such shares were registered under the Securities Act of 1933, as amended, pursuant to the Company's Registration Statement on Form S-1, which was declared effective by the SEC on June 26, 2013. The common shares are listed on the NASDAQ Global Select Market under the symbol “CDW.” The Company's common shares were sold to the underwriters at a price of $17.00 per share in the IPO and upon the exercise of the overallotment option, which generated aggregate net proceeds of approximately $429.5 million to the Company after deducting underwriting discounts, before expenses and transaction costs. Using a portion of the net proceeds from the IPO, the Company paid a $24.4 million termination fee to affiliates of the Sponsors in connection with the termination of the management services agreement with such entities that was effective upon completion of the IPO and redeemed $175.0 million aggregate principal amount of Senior Secured Notes. The redemption price of the Senior Secured Notes was 108.000% of the principal amount redeemed, plus $0.7 million of accrued and unpaid interest to the date of redemption. The Company used cash on hand to pay such accrued and unpaid interest. Following this redemption, $325.0 million aggregate principal amount of the Senior Secured Notes remain outstanding. In connection with this redemption, the Company expects to record a loss on extinguishment of long-term debt of $16.7 million in the consolidated statement of operations during the third quarter of 2013. This loss represents $14.0 million in redemption premium and $2.7 million for the write-off of a portion of the remaining deferred financing costs related to the Senior Secured Notes. On August 1, 2013, the Company redeemed $324.0 million aggregate principal amount of Senior Subordinated Notes. The Company used a portion of the net proceeds from the IPO to redeem $146.0 million aggregate principal amount of Senior Subordinated Notes and incremental borrowings of $190.0 million under the Term Loan to redeem $178.0 million aggregate principal amount of Senior Subordinated Notes. The redemption price of the Senior Subordinated Notes was 106.268% of the principal amount redeemed, plus $12.0 million of accrued and unpaid interest to the date of redemption. The Company used cash on hand to pay such accrued and unpaid interest. Following this redemption, $247.5 million aggregate principal amount of the Senior Subordinated Notes remain outstanding. In connection with this redemption, the Company expects to record a loss on extinguishment of long-term debt of $24.7 million in the consolidated statement of operations during the third quarter of 2013. This loss represents $20.3 million in redemption premium and $4.4 million for the write-off of a portion of the remaining deferred financing costs related to the Senior Subordinated Notes. The Company previously filed a claim as part of a class action settlement in a case alleging price fixing during the period of January 1, 1996 through December 31, 2006, by certain manufacturers of thin-film liquid crystal display panels. On July 13, 2013, the United Stated District Court for the Northern District of California approved distribution of the settlement proceeds, including a net payment to the Company of approximately $10.5 million after fees and expenses. The first of two settlement payments was received by the Company on July 29, 2013 in the amount of $8.5 million. The balance is expected to be received by year-end 2013.

Subsequent Events

On July 2, 2013, the Company completed an IPO of 23,250,000 shares of common stock. On July 31, 2013, the Company completed the sale of an additional 3,487,500 shares of common stock to the underwriters of the IPO pursuant to the underwriters' July 26, 2013 exercise in full of the overallotment option granted to them in connection with the IPO. Such shares were registered under the Securities Act of 1933, as amended, pursuant to the Company's Registration Statement on Form S-1, which was declared effective by the SEC on June 26, 2013. The common shares are listed on the NASDAQ Global Select Market under the symbol “CDW.” The Company's common shares were sold to the underwriters at a price of $17.00 per share in the IPO and upon the exercise of the overallotment option, which generated aggregate net proceeds of approximately $429.5 million to the Company after deducting underwriting discounts, before expenses and transaction costs.

Using a portion of the net proceeds from the IPO, the Company paid a $24.4 million termination fee to affiliates of the Sponsors in connection with the termination of the management services agreement with such entities that was effective upon completion of the IPO and redeemed $175.0 million aggregate principal amount of Senior Secured Notes. The redemption price of the Senior Secured Notes was 108.000% of the principal amount redeemed, plus $0.7 million of accrued and unpaid interest to the date of redemption. The Company used cash on hand to pay such accrued and unpaid interest. Following this redemption, $325.0 million aggregate principal amount of the Senior Secured Notes remain outstanding. In connection with this redemption, the Company expects to record a loss on extinguishment of long-term debt of $16.7 million in the consolidated statement of operations during the third quarter of 2013. This loss represents $14.0 million in redemption premium and $2.7 million for the write-off of a portion of the remaining deferred financing costs related to the Senior Secured Notes.

On August 1, 2013, the Company redeemed $324.0 million aggregate principal amount of Senior Subordinated Notes. The Company used a portion of the net proceeds from the IPO to redeem $146.0 million aggregate principal amount of Senior Subordinated Notes and incremental borrowings of $190.0 million under the Term Loan to redeem $178.0 million aggregate principal amount of Senior Subordinated Notes. The redemption price of the Senior Subordinated Notes was 106.268% of the principal amount redeemed, plus $12.0 million of accrued and unpaid interest to the date of redemption. The Company used cash on hand to pay such accrued and unpaid interest. Following this redemption, $247.5 million aggregate principal amount of the Senior Subordinated Notes remain outstanding. In connection with this redemption, the Company expects to record a loss on extinguishment of long-term debt of $24.7 million in the consolidated statement of operations during the third quarter of 2013. This loss represents $20.3 million in redemption premium and $4.4 million for the write-off of a portion of the remaining deferred financing costs related to the Senior Subordinated Notes.

The Company previously filed a claim as part of a class action settlement in a case alleging price fixing during the period of January 1, 1996 through December 31, 2006, by certain manufacturers of thin-film liquid crystal display panels. On July 13, 2013, the United Stated District Court for the Northern District of California approved distribution of the settlement proceeds, including a net payment to the Company of approximately $10.5 million after fees and expenses. The first of two settlement payments was received by the Company on July 29, 2013 in the amount of $8.5 million. The balance is expected to be received by year-end 2013.