Interim Financial Statements (Details 2) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) item	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Nov. 30, 2014	Aug. 31, 2012
Combined financial information regarding entities accounted for as discontinued operations
Number of entities newly classified as held for sale | item				0
Balance Sheet information regarding entities accounted for as discontinued operations
Total assets		$ 15.3		$ 15.3		$ 156.1
Total liabilities		8.3		8.3		108.2
Fair Value of Financial Instruments
Debt instrument, Carrying Value		$ 1,184.9		$ 1,184.9		$ 1,353.2
5.75% Senior Subordinated Notes Due 2022
Fair Value of Financial Instruments
Interest rate (as a percent)		5.75%		5.75%		5.75%		5.75%
Debt instrument, Carrying Value		$ 550.0		$ 550.0		$ 550.0
5.75% Senior Subordinated Notes Due 2022 | Level 2
Fair Value of Financial Instruments
Debt instrument, Fair Value		$ 560.6		$ 560.6		$ 558.4
5.375% Senior Subordinated Notes Due 2024
Fair Value of Financial Instruments
Interest rate (as a percent)		5.375%		5.375%		5.375%	5.375%
Debt instrument, Carrying Value		$ 300.0		$ 300.0		$ 300.0
5.375% Senior Subordinated Notes Due 2024 | Level 2
Fair Value of Financial Instruments
Debt instrument, Fair Value		299.6		299.6		306.0
Mortgage Facilities
Fair Value of Financial Instruments
Debt instrument, Carrying Value		167.8		167.8		169.7
Mortgage Facilities | Level 2
Fair Value of Financial Instruments
Debt instrument, Fair Value		169.7		169.7		171.6
Disposal group reclassified as held and used
Discontinued Operation, Reclassified as Held and Used
Revenue		17.4	$ 15.3	45.4	$ 39.3
Pre-tax loss		(0.2)	(0.4)	(0.7)	(0.7)
Hertz car rental franchise
Combined financial information regarding entities accounted for as discontinued operations
Proceeds from sale of business	$ 17.8
Retail Automotive and Hertz car rental franchise | Held-for-sale
Combined financial information regarding entities accounted for as discontinued operations
Revenues		15.1	46.7	63.1	167.9
Pre-tax loss		(0.1)	$ (3.2)	(4.8)	(19.3)
Pre-tax gain on disposal				2.9	$ 14.8
Balance Sheet information regarding entities accounted for as discontinued operations
Inventories		6.6		6.6		17.5
Other assets		8.7		8.7		138.6
Total assets		15.3		15.3		156.1
Floor plan notes payable (including non-trade)		4.3		4.3		14.6
Other liabilities		4.0		4.0		93.6
Total liabilities		$ 8.3		$ 8.3		$ 108.2