Interim Financial Statements (Business and Basis of Presentation) (Details)	3 Months Ended
	Mar. 31, 2017 brand stores franchises
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Owned and operated new vehicle franchises | franchises	372
Number of stores | stores	259
Number of brands | brand	35
Percentage of new vehicle sales from core brands	93.00%
Owned and operated collision centers	70