Consolidated Statement Of Shareholders' (Deficit) Equity (USD $) In Millions, except Share data	Total	Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Preferred Stock [Member]	Common Stock [Member]
Balance at at Dec. 31, 2010	$ (43.5)	$ 2,165.3	$ (2,208.0)	$ (2.2)	$ 0	$ 1.4
Preferred Stock, Shares Issued					0
Common Stock, Shares, Issued						144,900,000
Equity-based compensation expense	19.5	19.5	0	0	0	0
Stock Issued During Period, Shares, Equity-based compensation expense					0	0
Investment from CDW Holdings LLC	1.0	1.0	0	0	0	0
Stock Issued During Period, Shares, Investment from Parent					0	0
Repurchase of Class B Common Shares	(0.4)	0	(0.4)	0	0	0
Treasury Stock, Shares, Acquired					0	0
Accrued charitable contribution related to the MPK Coworker Incentive Plan II, net of tax	(1.1)	(1.1)	0	0	0	0
Stock Issued During Period, Shares, Accrued Charitable Contribution related to the MPK Coworker Incentive Plan II					0	300,000
Net income (loss)	17.1	0	17.1	0	0	0
Stock Issued During Period, Shares, Net Income (Loss) Attributable to Parent					0	0
Reclassification of realized loss on interest rate swap agreements from accumulated other comprehensive loss to net income (loss), net of tax	1.9	0	0	1.9	0	0
Stock Issued During Period, Shares, Reclassification Adjustment from AOCI to Derivatives					0	0
Foreign currency translation adjustment	(1.8)	0	0	(1.8)	0	0
Stock Issued During Period, Shares, Foreign Currency Translation Adjustment					0	0
Balance at at Dec. 31, 2011	(7.3)	2,184.7	(2,191.3)	(2.1)	0	1.4
Preferred Stock, Shares Issued	0				0
Preferred Stock, Value, Issued	0
Common Stock, Value, Issued	1.4
Common Stock, Shares, Issued	145,200,000					145,200,000
Equity-based compensation expense	22.1	22.1	0	0	0	0
Stock Issued During Period, Shares, Equity-based compensation expense					0	0
Investment from CDW Holdings LLC	2.8	2.8	0	0	0	0
Stock Issued During Period, Shares, Investment from Parent					0	0
Repurchase of Class B Common Shares	(0.7)	0	(0.7)	0	0	0
Treasury Stock, Shares, Acquired					0	0
Accrued charitable contribution related to the MPK Coworker Incentive Plan II, net of tax	(1.4)	(1.4)	0	0	0	0
Stock Issued During Period, Shares, Accrued Charitable Contribution related to the MPK Coworker Incentive Plan II					0	300,000
MPK Coworker Incentive Plan II units withheld for taxes	(0.5)	(0.5)	0	0	0	0
Stock Issued During Period, Shares, Incentive Compensation Plan units withheld for taxes					0	0
Net income (loss)	119.0	0	119.0	0	0	0
Stock Issued During Period, Shares, Net Income (Loss) Attributable to Parent					0	0
Reclassification of realized loss on interest rate swap agreements from accumulated other comprehensive loss to net income (loss), net of tax	0
Foreign currency translation adjustment	2.5	0	0	2.5	0	0
Stock Issued During Period, Shares, Foreign Currency Translation Adjustment					0	0
Balance at at Dec. 31, 2012	136.5	2,207.7	(2,073.0)	0.4	0	1.4
Preferred Stock, Shares Issued	0				0
Preferred Stock, Value, Issued	0
Common Stock, Value, Issued	1.7
Common Stock, Shares, Issued	172,000,000					172,000,000
Equity-based compensation expense	46.6	46.6	0	0	0	0
Stock Issued During Period, Shares, Equity-based compensation expense					0	0
Stock Issued During Period, Value, New Issues	424.7	424.4	0	0	0	0.3
Stock Issued During Period, Shares, New Issues					0	26,800,000
Repurchase of Class B Common Shares	(0.2)	0	(0.2)	0	0	0
Treasury Stock, Shares, Acquired					0	0
Dividends, Common Stock	(7.3)	0	(7.3)	0	0	0
Stock Dividends, Shares					0	0
Reclassification to goodwill for accrued charitable contributions	9.4	9.4	0	0	0	0
Stock Issued During Period, Shares, Reclassification to Goodwill for accrued charitable contributions					0	0
MPK Coworker Incentive Plan II units withheld for taxes	(24.1)	0	(24.1)	0	0	0
Stock Issued During Period, Shares, Incentive Compensation Plan units withheld for taxes					0	0
Net income (loss)	132.8	0	132.8	0	0	0
Stock Issued During Period, Shares, Net Income (Loss) Attributable to Parent					0	0
Reclassification of realized loss on interest rate swap agreements from accumulated other comprehensive loss to net income (loss), net of tax	0
Foreign currency translation adjustment	(6.7)	0	0	(6.7)	0	0
Stock Issued During Period, Shares, Foreign Currency Translation Adjustment					0	0
Balance at at Dec. 31, 2013	$ 711.7	$ 2,688.1	$ (1,971.8)	$ (6.3)	$ 0	$ 1.7