Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 59.4	$ 46.4
Adjustments to reconcile net income to net cash used in operating activities—
Depreciation and amortization	16.9	16.8
Stock-based compensation	5.6	7.7
Deferred income taxes	9.3	10.1
Loss on extinguishment of debt	0	0.4
Loaner vehicle amortization	6.7	6.0
Excess tax benefit on share-based arrangements	(5.4)	(1.4)
Impairment expenses	2.3	0
Gain on sale of assets, net	(1.2)	(26.8)
Other adjustments, net	7.3	5.4
Changes in operating assets and liabilities, net of acquisitions and divestitures—
Contracts-in-transit	19.2	16.8
Accounts receivable	(12.3)	10.5
Proceeds from the sale of accounts receivable	14.3	16.9
Inventories	(37.5)	108.7
Other current assets	(50.3)	(24.0)
Floor plan notes payable—trade	(21.4)	(109.2)
Floor plan notes payable—trade divestitures	0	(23.0)
Accounts payable and accrued liabilities	1.1	6.9
Deferred compensation plan excess funding refund	3.2	0
Other long-term assets and liabilities, net	(0.6)	2.2
Net cash provided by operating activities	16.6	70.4
CASH FLOW FROM INVESTING ACTIVITIES:
Capital expenditures—excluding real estate	(33.8)	(16.3)
Purchases of real estate	(6.5)	(30.3)
Purchases of previously leased real estate	(8.6)	(17.4)
Proceeds from the sale of assets	4.3	91.9
Other investing activities	0	0.6
Net cash (used in) provided by investing activities	(44.6)	28.5
CASH FLOW FROM FINANCING ACTIVITIES:
Floor plan borrowings—non-trade	2,186.6	295.4
Floor plan repayments—non-trade	(2,129.0)	(303.7)
Floor plan repayments—non-trade divestitures	(2.1)	(14.8)
Proceeds from borrowings	34.1	0
Repayments of borrowings	(58.4)	(59.8)
Payment of debt issuance costs	(0.3)	(0.1)
Repurchases of common stock, including those associated with net share settlement of employee share-based awards	(17.7)	(33.4)
Excess tax benefit on share-based arrangements	5.4	1.4
Proceeds from the exercise of stock options	3.9	3.0
Net cash provided by (used in) financing activities	22.5	(112.0)
Net decrease in cash and cash equivalents	(5.5)	(13.1)
CASH AND CASH EQUIVALENTS, beginning of period	11.4	21.3
CASH AND CASH EQUIVALENTS, end of period	$ 5.9	$ 8.2