Interim Financial Statements (Details 2) (USD $) In Millions, unless otherwise specified												3 Months Ended		9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 5.75% senior subordinated notes due 2022	Dec. 31, 2013 5.75% senior subordinated notes due 2022	Dec. 31, 2012 5.75% senior subordinated notes due 2022	Sep. 30, 2014 5.75% senior subordinated notes due 2022 Level 2	Dec. 31, 2013 5.75% senior subordinated notes due 2022 Level 2	Sep. 30, 2014 Mortgage facilities	Dec. 31, 2013 Mortgage facilities	Sep. 30, 2014 Mortgage facilities Level 2	Dec. 31, 2013 Mortgage facilities Level 2	Sep. 30, 2014 Retail	Sep. 30, 2013 Retail	Sep. 30, 2014 Retail	Sep. 30, 2013 Retail	Dec. 31, 2013 Retail
Combined financial information regarding entities accounted for as discontinued operations
Revenues												$ 25.4	$ 80.1	$ 101.6	$ 351.8
Pre-tax income (loss)												(2.5)	(0.6)	(18.7)	(1.2)
Pre-tax gain (loss) on disposal														14.8	0.8
Balance Sheet information regarding entities accounted for as discontinued operations
Inventories												22.7		22.7		55.8
Other assets												22.9		22.9		51.5
Assets Held-for-sale, Current, Total	45.6	107.3										45.6		45.6		107.3
Floor plan notes payable (including non-trade)												18.3		18.3		43.6
Other liabilities												15.4		15.4		16.1
Total liabilities	33.7	59.7										33.7		33.7		59.7
Interest rate (as a percent)			5.75%	5.75%	5.75%
Fair Value of Financial Instruments
Debt instrument, Carrying Value	1,233.4	1,083.2	550.0	550.0				130.9	118.6
Debt instrument, Fair Value						$ 567.6	$ 565.1			$ 131.6	$ 117.0