Interim Financial Statements (Details 2) (USD $) In Millions, unless otherwise specified												3 Months Ended		6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 5.75% senior subordinated notes due 2022	Dec. 31, 2013 5.75% senior subordinated notes due 2022	Aug. 31, 2012 5.75% senior subordinated notes due 2022	Jun. 30, 2014 5.75% senior subordinated notes due 2022 Level 2	Dec. 31, 2013 5.75% senior subordinated notes due 2022 Level 2	Jun. 30, 2014 Mortgage facilities	Dec. 31, 2013 Mortgage facilities	Jun. 30, 2014 Mortgage facilities Level 2	Dec. 31, 2013 Mortgage facilities Level 2	Jun. 30, 2014 Retail	Jun. 30, 2013 Retail	Jun. 30, 2014 Retail	Jun. 30, 2013 Retail	Dec. 31, 2013 Retail
Combined financial information regarding entities accounted for as discontinued operations
Revenues												$ 29.6	$ 135.4	$ 76.2	$ 271.7
Pre-tax income (loss)												(8.0)	(1.6)	(16.2)	(0.6)
Pre-tax gain (loss) on disposal													0.8	14.8	0.8
Balance Sheet information regarding entities accounted for as discontinued operations
Inventories												29.2		29.2		55.8
Other assets												23.2		23.2		51.5
Total assets												52.4		52.4		107.3
Floor plan notes payable (including non-trade)												20.0		20.0		43.6
Other liabilities												21.1		21.1		16.1
Total liabilities	41.1	59.7										41.1		41.1		59.7
Interest rate (as a percent)			5.75%	5.75%	5.75%
Fair Value of Financial Instruments
Debt instrument, Carrying Value	1,088.4	1,083.2	550.0	550.0				130.4	118.6
Debt instrument, Fair Value						$ 578.9	$ 565.1			$ 131.2	$ 117.0