Acquisitions and Dispositions Acquisitions and Dispositions (Details textuals) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Total assets	$ 4,098,467,000	4,141,492,000
Business Combination, Consideration Transferred		336,600,000
UNITED STATES
Business Acquisition [Line Items]
Number of Franchises Disposed	1
Number Of Dealerships Acquired	1	7
Number of franchises awarded		2
Business Acquisition Purchase Price Allocation Goodwill	103,900,000
UNITED KINGDOM
Business Acquisition [Line Items]
Number Of Dealerships Acquired		3
Business Acquisition Purchase Price Allocation Goodwill	18,400,000
BRAZIL
Business Acquisition [Line Items]
Number Of Dealerships Acquired		1
Number of franchises awarded		1
Business Acquisition Purchase Price Allocation Goodwill	0
Businesses acquired [Member]
Business Acquisition [Line Items]
Total assets		411,340,000