Vehicle Financing (Details)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Vehicle Financing
Weighted average interest rate on floor plan borrowings (as a percent)	1.50%	1.70%	1.90%

Weighted average interest rate of debt outstanding.

No definition available.

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant