Unaudited Condensed Consolidated Statements Of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES:
Net income	$ 212.0	$ 159.3
Adjustments to reconcile net income to net cash provided by operating activities:
Loss from discontinued operations	2.3	7.9
Depreciation and amortization	62.7	57.2
Amortization of debt issuance costs and discounts	3.2	2.4
Stock-based compensation expense	15.7	13.6
Deferred income tax provision	15.9	10.9
Non-cash impairment charges	0	3.7
Write-off of deferred debt issuance costs	0	3.5
Net loss (gain) on asset sales and dispositions	(3.0)	0.4
Other	(0.2)	1.2
(Increase) decrease, net of effects from business combinations and divestitures:
Receivables	57.5	11.8
Inventory	277.6	(321.5)
Other assets	(10.5)	27.2
Increase (decrease), net of effects from business combinations and divestitures:
Vehicle floorplan payable-trade, net	(336.7)	174.2
Accounts payable	5.0	32.1
Other liabilities	9.3	12.5
Net cash provided by continuing operations	310.8	196.4
Net cash provided by discontinued operations	0.3	1.3
Net cash provided by operating activities	311.1	197.7
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(113.8)	(77.7)
Property operating lease buy-outs	(13.8)	(2.6)
Proceeds from the sale of property and equipment	3.0	0.2
Proceeds from assets held for sale	9.0	5.8
Insurance recoveries on property and equipment	0	1.8
Cash used in business acquisitions, net of cash acquired	(64.2)	(73.1)
Proceeds from the sale of restricted investments	0	1.3
Cash received from business divestitures, net of cash relinquished	4.9	12.4
Other	0.2	(1.1)
Net cash used in continuing operations	(174.7)	(133.0)
Net cash used in discontinued operations	0	(0.3)
Net cash used in investing activities	(174.7)	(133.3)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repurchases of common stock	(335.0)	(507.3)
Proceeds from revolving credit facilities	300.0	325.0
Payment of revolving credit facilities	(180.0)	(115.0)
Proceeds from 6.75% Senior Notes due 2018	0	394.0
Payment of term loan facility	0	(66.6)
Payment of debt issuance costs	0	(11.9)
Net proceeds from (payments of) vehicle floorplan payable - non-trade	(28.3)	61.8
Payments of mortgage facilities	(5.7)	(5.4)
Payments of long-term debt	(0.5)	(0.3)
Proceeds from the exercise of stock options	66.3	30.1
Tax benefit from stock-based awards	19.0	6.3
Net cash used in continuing operations	(164.2)	(153.3)
Net cash provided by discontinued operations	0	(0.1)
Net cash used in financing activities	(164.2)	(153.4)
DECREASE IN CASH AND CASH EQUIVALENTS	(27.8)	(89.0)
CASH AND CASH EQUIVALENTS at beginning of period	95.1	173.5
CASH AND CASH EQUIVALENTS at end of period	67.3	84.5
Payment of Floating Rate Senior Notes due 2013 [Member]
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Payment of Senior Unsecured Notes	0	(146.1)
Payment of 7% Senior Notes due 2014 [Member]
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Payment of Senior Unsecured Notes	$ 0	$ (117.9)