Goodwill and Intangible Assets, Net (Goodwill) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		$ 3,113,300,000	$ 3,111,900,000
Goodwill, Impaired, Accumulated Impairment Loss		(1,928,300,000)	(1,610,000,000)
Goodwill, beginning balance		1,185,000,000	1,501,900,000
Acquisitions, dispositions, and other adjustments, net	[1]	50,300,000	1,400,000
Gain/(Loss) on goodwill impairment		0	(318,300,000)	$ 0
Goodwill, gross, ending balance		3,163,600,000	3,113,300,000	3,111,900,000
Goodwill, Impaired, Accumulated Impairment Loss		(1,928,300,000)	(1,928,300,000)	(1,610,000,000)
Goodwill, ending balance		1,235,300,000	1,185,000,000	1,501,900,000
Reporting Unit, Domestic [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		367,200,000	367,300,000
Goodwill, Impaired, Accumulated Impairment Loss		(140,000,000.0)	(140,000,000.0)
Goodwill, beginning balance		227,200,000	227,300,000
Acquisitions, dispositions, and other adjustments, net	[1]	1,500,000	(100,000)
Gain/(Loss) on goodwill impairment			0
Goodwill, gross, ending balance		368,700,000	367,200,000	367,300,000
Goodwill, Impaired, Accumulated Impairment Loss		(140,000,000.0)	(140,000,000.0)	(140,000,000.0)
Goodwill, ending balance		228,700,000	227,200,000	227,300,000
Reporting Unit, Import [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		500,600,000	498,900,000
Goodwill, Impaired, Accumulated Impairment Loss		0	0
Goodwill, beginning balance		500,600,000	498,900,000
Acquisitions, dispositions, and other adjustments, net	[1]	17,300,000	1,700,000
Gain/(Loss) on goodwill impairment			0
Goodwill, gross, ending balance		517,900,000	500,600,000	498,900,000
Goodwill, Impaired, Accumulated Impairment Loss		0	0	0
Goodwill, ending balance		517,900,000	500,600,000	498,900,000
Reporting Unit, Premium Luxury [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		714,600,000	714,900,000
Goodwill, Impaired, Accumulated Impairment Loss		(257,400,000)	0
Goodwill, beginning balance		457,200,000	714,900,000
Acquisitions, dispositions, and other adjustments, net	[1]	26,900,000	(300,000)
Gain/(Loss) on goodwill impairment			(257,400,000)
Goodwill, gross, ending balance		741,500,000	714,600,000	714,900,000
Goodwill, Impaired, Accumulated Impairment Loss		(257,400,000)	(257,400,000)	0
Goodwill, ending balance		484,100,000	457,200,000	714,900,000
Reporting Unit, Collision Centers [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		41,600,000	41,700,000
Goodwill, Impaired, Accumulated Impairment Loss		(41,600,000)	0
Goodwill, beginning balance		0	41,700,000
Acquisitions, dispositions, and other adjustments, net	[1]	4,600,000	(100,000)
Gain/(Loss) on goodwill impairment			(41,600,000)
Goodwill, gross, ending balance		46,200,000	41,600,000	41,700,000
Goodwill, Impaired, Accumulated Impairment Loss		(41,600,000)	(41,600,000)	0
Goodwill, ending balance		4,600,000	0	41,700,000
Reporting Unit, Parts Centers [Member]
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		19,300,000	19,100,000
Goodwill, Impaired, Accumulated Impairment Loss		(19,300,000)	0
Goodwill, beginning balance		0	19,100,000
Acquisitions, dispositions, and other adjustments, net	[1]	0	200,000
Gain/(Loss) on goodwill impairment			(19,300,000)
Goodwill, gross, ending balance		19,300,000	19,300,000	19,100,000
Goodwill, Impaired, Accumulated Impairment Loss		(19,300,000)	(19,300,000)	0
Goodwill, ending balance		0	0	19,100,000
Single Reporting Unit (before change in reporting units)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance		1,470,000,000	1,470,000,000
Goodwill, Impaired, Accumulated Impairment Loss		(1,470,000,000)	(1,470,000,000)
Goodwill, beginning balance		0	0
Acquisitions, dispositions, and other adjustments, net	[1]	0	0
Gain/(Loss) on goodwill impairment			0
Goodwill, gross, ending balance		1,470,000,000	1,470,000,000	1,470,000,000
Goodwill, Impaired, Accumulated Impairment Loss		(1,470,000,000)	(1,470,000,000)	(1,470,000,000)
Goodwill, ending balance		$ 0	$ 0	$ 0

[1] Includes amounts reclassified to held for sale and related adjustments, which are presented in Other Current Assets in our Consolidated Balance Sheet as of period end.