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Percentage increase in revenue.

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Interim Financial Statements - COVID-19 Disclosure (Details) $ in Millions	1 Months Ended	2 Months Ended		3 Months Ended
	Mar. 31, 2020 USD ($) item	Mar. 31, 2020 USD ($) employee	Feb. 29, 2020	Mar. 31, 2020 USD ($) item	Mar. 31, 2019 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
COVID-19 Overview
Revenues				$ 5,009.1	$ 5,564.4
Cash	$ 431.9	$ 431.9		431.9	$ 43.5		$ 28.1	$ 39.4
Available funds, revolving credit facilities	450.0	450.0		450.0		$ 700.0
Available funds, potentially financeable real estate	450.0	450.0		$ 450.0
PTL
COVID-19 Overview
Ownership interest in PTS (as a percent)				28.90%
Minimum
COVID-19 Overview
Cash	$ 430.0	$ 430.0		$ 430.0		$ 221.0
3.75% senior subordinated notes due 2020
COVID-19 Overview
Interest rate (as a percent)	3.75%	3.75%		3.75%			3.75%
Principal amount	$ 300.0	$ 300.0		$ 300.0
Retail Automotive Dealership \| New vehicle
COVID-19 Overview
Percentage increase in revenue			5.30%
Retail Automotive Dealership \| Used vehicle
COVID-19 Overview
Percentage increase in revenue			7.30%
Retail Automotive Dealership \| Finance and insurance, net
COVID-19 Overview
Percentage increase in revenue			10.70%
Retail Automotive Dealership \| Service and parts
COVID-19 Overview
Percentage increase in revenue			3.00%
COVID-19 Risk
COVID-19 Overview
Estimated capital expenditures postponed				$ 150.0
Temporary reduction in the salary for the CEO and President, percentage				100.00%
Temporary reduction in the salary for other executive officers, percentage				25.00%
Incentive financing (as percent)	0.00%
COVID-19 Risk \| PTL
COVID-19 Overview
Number of layoffs \| item				7,000
Percentage reduction in executive management pay				30.00%
COVID-19 Risk \| Minimum
COVID-19 Overview
Number of employees furloughed \| employee		15,000
COVID-19 Risk \| UK \| Minimum
COVID-19 Overview
Percentage of employees furloughed				90.00%
COVID-19 Risk \| Retail Automotive Dealership \| U.S.
COVID-19 Overview
Percentage decline in unit volume	40.10%
COVID-19 Risk \| Retail Automotive Dealership \| UK
COVID-19 Overview
Percentage decline in unit volume	38.00%
COVID-19 Risk \| Retail Automotive Dealership \| New and Used Vehicle
COVID-19 Overview
Percentage decline in same store business	40.20%
COVID-19 Risk \| Retail Automotive Dealership \| Used vehicle
COVID-19 Overview
Percentage decline in same store unit sales	49.00%
Number of used vehicle supercenters that were closed \| item	16
COVID-19 Risk \| Retail Automotive Dealership \| Service and parts
COVID-19 Overview
Percentage decline in business	24.50%
COVID-19 Risk \| Retail Automotive Dealership \| Service and parts \| U.S.
COVID-19 Overview
Percentage decline in revenue compared to the prior year	21.20%
COVID-19 Risk \| Retail Automotive Dealership \| Service and parts \| UK
COVID-19 Overview
Percentage decline in revenue compared to the prior year	29.50%
COVID-19 Risk \| Retail Commercial Truck Dealership
COVID-19 Overview
Percentage increase in total units retailed				52.40%
Percentage increase in revenue				47.90%
Revenues				$ 491.4
COVID-19 Risk \| Retail Commercial Truck Dealership \| Service and parts
COVID-19 Overview
Percentage decline in same store business	6.60%
COVID-19 Risk \| Retail Commercial Truck Dealership \| North American Class 8 Retail
COVID-19 Overview
Percentage decline in business				26.00%
Percentage decline in same store business				1.70%
Percentage decline in same store unit sales				2.20%