Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES:
Net income	$ 303.3	$ 283.3
Adjustments to reconcile net income to net cash provided by operating activities:
(Income) loss from discontinued operations	(0.3)	0.2
Depreciation and amortization	124.0	118.0
Amortization of debt issuance costs and accretion of debt discounts	4.2	4.2
Stock-based compensation expense	22.0	18.1
Deferred income tax provision	12.4	7.7
Net gain related to business/property dispositions	(38.5)	(43.8)
Franchise rights impairment	8.1	0.0
Non-cash impairment charges and valuation adjustments	2.2	0.0
Other	(2.5)	(5.2)
(Increase) decrease, net of effects from business combinations and divestitures:
Receivables	309.4	143.6
Inventory	(44.9)	94.1
Other assets	(101.3)	(21.2)
Increase (decrease), net of effects from business combinations and divestitures:
Vehicle floorplan payable - trade, net	(42.5)	(212.7)
Accounts payable	(28.1)	(25.6)
Other liabilities	7.0	96.6
Net cash provided by continuing operations	534.5	457.3
Net cash provided by (used in) discontinued operations	0.6	(0.3)
Net cash provided by operating activities	535.1	457.0
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(283.2)	(227.6)
Property operating lease buy-outs	0.0	(3.3)
Proceeds from the sale of property and equipment	24.0	2.6
Proceeds from assets held for sale	10.2	34.7
Insurance recoveries on property and equipment	1.1	1.2
Cash received from business divestitures, net of cash relinquished	144.2	47.8
Cash used in business acquisitions, net of cash acquired	(67.9)	(56.9)
Other	(0.6)	(2.0)
Net cash used in continuing operations	(172.2)	(203.5)
Net cash used in discontinued operations	0.0	0.0
Net cash used in investing activities	(172.2)	(203.5)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repurchases of common stock	(100.0)	(425.2)
Payment of 6.75% Senior Notes due 2018	(400.0)	0.0
Proceeds from revolving credit facility	0.0	907.0
Payments of revolving credit facility	0.0	(825.0)
Net proceeds from commercial paper	270.0	53.0
Net proceeds from (payments of) vehicle floorplan payable - non-trade	(147.6)	15.4
Payments of mortgage facility	0.0	(7.6)
Payments of capital leases and other debt obligations	(13.9)	(3.5)
Proceeds from the exercise of stock options	16.0	24.7
Payments of tax withholdings for stock-based awards	(2.7)	(1.1)
Other	(2.5)	0.0
Net cash used in continuing operations	(380.7)	(262.3)
Net cash used in discontinued operations	0.0	0.0
Net cash used in financing activities	(380.7)	(262.3)
DECREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(17.8)	(8.8)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH at beginning of period	71.1	65.4
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH at end of period	$ 53.3	$ 56.6