Unaudited Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES:
Net income (loss)	$ (232.3)	$ 92.0
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss from discontinued operations	0.1	0.1
Depreciation and amortization	48.1	44.1
Amortization of debt issuance costs and accretion of debt discounts	1.2	1.3
Stock-based compensation expense	4.5	13.7
Deferred income tax provision (benefit)	(68.6)	0.8
Net gain related to business/property dispositions	0.0	(8.3)
Goodwill impairment	318.3	0.0
Franchise rights impairment	57.5	0.0
Non-cash impairment charges	8.5	0.2
Other	3.6	(2.0)
(Increase) decrease, net of effects from business acquisitions and divestitures:
Receivables	403.4	193.3
Inventory	(371.3)	(141.4)
Other assets	(3.5)	33.2
Increase (decrease), net of effects from business acquisitions and divestitures:
Vehicle floorplan payable - trade, net	76.6	65.7
Accounts payable	(64.1)	(35.2)
Other liabilities	(68.3)	2.2
Net cash provided by continuing operations	113.7	259.7
Net cash provided by discontinued operations	0.0	0.0
Net cash provided by operating activities	113.7	259.7
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(42.2)	(60.0)
Insurance recoveries on property and equipment	1.2	0.3
Cash received from business divestitures, net of cash relinquished	0.0	17.4
Cash used in business acquisitions, net of cash acquired	(0.4)	(4.3)
Investment in equity security	(50.0)	0.0
Other	(0.8)	(2.0)
Net cash used in continuing operations	(92.2)	(48.6)
Net cash used in discontinued operations	0.0	0.0
Net cash used in investing activities	(92.2)	(48.6)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repurchases of common stock	(78.9)	(33.4)
Payment of 5.5% Senior Notes due 2020	(350.0)	0.0
Proceeds from revolving credit facility	790.0	0.0
Net payments of commercial paper	(30.0)	(160.0)
Payment of debt issuance costs	(6.1)	0.0
Net proceeds from (payments of) vehicle floorplan payable - non-trade	30.1	(12.5)
Payments of other debt obligations	(1.1)	(2.6)
Proceeds from the exercise of stock options	1.0	0.3
Payments of tax withholdings for stock-based awards	(7.9)	(2.7)
Net cash received from (used in) continuing operations	347.1	(210.9)
Net cash used in discontinued operations	0.0	0.0
Net cash received from (used in) financing activities	347.1	(210.9)
INCREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	368.6	0.2
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH at beginning of period	42.5	49.4
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH at end of period	$ 411.1	$ 49.6