Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES:
Net income	$ 283.3	$ 315.2
Adjustments to reconcile net income to net cash provided by operating activities:
Loss from discontinued operations	0.2	0.9
Depreciation and amortization	118.0	107.0
Amortization of debt issuance costs and accretion of debt discounts	4.2	4.0
Stock-based compensation expense	18.1	22.5
Deferred income tax provision	7.7	2.6
Net gain related to business/property dispositions	(43.8)	(29.7)
Non-cash impairment charges and valuation adjustments	0.0	14.0
Excess tax benefit from stock-based awards	0.0	(0.7)
Other	(5.2)	(2.4)
(Increase) decrease, net of effects from business combinations and divestitures:
Receivables	143.6	137.5
Inventory	94.1	320.4
Other assets	(21.2)	(38.2)
Increase (decrease), net of effects from business combinations and divestitures:
Vehicle floorplan payable - trade, net	(212.7)	(418.2)
Accounts payable	(25.6)	(3.9)
Other liabilities	96.6	48.6
Net cash provided by continuing operations	457.3	479.6
Net cash used in discontinued operations	(0.3)	(0.8)
Net cash provided by operating activities	457.0	478.8
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(227.6)	(187.6)
Property operating lease buy-outs	(3.3)	(5.0)
Proceeds from the sale of property and equipment	2.6	7.2
Proceeds from assets held for sale	34.7	0.0
Insurance recoveries on property and equipment	1.2	0.0
Cash received from business divestitures, net of cash relinquished	47.8	87.5
Cash used in business acquisitions, net of cash acquired	(56.9)	(362.5)
Net change in restricted cash	(2.7)	3.8
Other	(2.0)	(0.2)
Net cash used in continuing operations	(206.2)	(456.8)
Net cash used in discontinued operations	0.0	0.0
Net cash used in investing activities	(206.2)	(456.8)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repurchases of common stock	(426.3)	(470.6)
Proceeds from revolving credit facility	907.0	1,050.0
Payments of revolving credit facility	(825.0)	(1,050.0)
Net proceeds from commercial paper	53.0	375.5
Net proceeds from vehicle floorplan payable - non-trade	15.4	78.7
Purchase of subsidiary shares	0.0	(15.2)
Payments of mortgage facility	(7.6)	(7.7)
Payments of capital leases and other debt obligations	(3.5)	(3.1)
Proceeds from the exercise of stock options	24.7	7.8
Excess tax benefit from stock-based awards	0.0	0.7
Net cash used in continuing operations	(262.3)	(33.9)
Net cash used in discontinued operations	0.0	0.0
Net cash used in financing activities	(262.3)	(33.9)
DECREASE IN CASH AND CASH EQUIVALENTS	(11.5)	(11.9)
CASH AND CASH EQUIVALENTS at beginning of period	64.8	74.1
CASH AND CASH EQUIVALENTS at end of period	$ 53.3	$ 62.2