Exit or Disposal Cost Obligations (Details) - AutoNation Collision Parts Closure [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		$ 36.7
Contract Termination Charges, Other Associated Closing Costs, and Involuntary Termination Benefits [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Liability for exit or disposal costs, beginning balance	$ 3.4
Costs incurred	0.0
Costs paid or otherwise settled	(3.4)
Liability for exit or disposal costs, ending balance	0.0	3.4
Contract Termination [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Liability for exit or disposal costs, beginning balance	0.2
Costs incurred	0.0
Costs paid or otherwise settled	(0.2)
Liability for exit or disposal costs, ending balance	0.0	0.2
Other Restructuring [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Liability for exit or disposal costs, beginning balance	2.4
Costs incurred	0.0
Costs paid or otherwise settled	(2.4)
Liability for exit or disposal costs, ending balance	0.0	2.4
Employee Severance [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Liability for exit or disposal costs, beginning balance	0.8
Costs incurred	0.0
Costs paid or otherwise settled	(0.8)
Liability for exit or disposal costs, ending balance	$ 0.0	0.8
Other Operating Income (Expense) [Member] | Asset Impairment Charges [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		5.1
Other Operating Income (Expense) [Member] | Contract Termination [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		3.2
Selling, General and Administrative Expenses [Member] | Accelerated Amortization [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		3.2
Selling, General and Administrative Expenses [Member] | Other Restructuring [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		2.6
Selling, General and Administrative Expenses [Member] | Employee Severance [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		1.1
Depreciation and amortization [Member] | Accelerated Depreciation [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		3.9
Parts and Service [Member] | Cost of Sales [Member] | Inventory Valuation Adjustment [Member]
Liability for Exit or Disposal Costs [Roll Forward]
Costs incurred		$ 17.6