Acquisitions and Dispositions (Details textuals)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Acquisitions and Dispositions (Textual) [Abstract]
Number of franchises disposed	3	10
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 120,300,000	$ 0
Cash received in acquisition		3,900,000
Proceeds From Disposition Of Franchise Property And Equipment	10,708,000	36,843,000	$ 41,581,000
Payments to Acquire Businesses, Net of Cash Acquired	$ 109,081,000	57,327,000	$ 212,252,000
Net Gain (Loss) on Real Estate and Dealership Transactions		$ 2,200,000
Brazil
Acquisitions and Dispositions (Textual) [Abstract]
Number Of Dealerships Acquired		1
Number of franchises disposed	2	4
Number of franchises awarded		2
Number of franchises acquired		1
Number Of Dealerships Opened		2
Net Gain (Loss) on Real Estate and Dealership Transactions		$ (800,000)
U.S.
Acquisitions and Dispositions (Textual) [Abstract]
Number Of Dealerships Acquired	3
Number of franchises disposed		5
Number of franchises awarded	1
Number of franchises acquired	4
Number Of Dealerships Opened	1
Net Gain (Loss) on Real Estate and Dealership Transactions		$ 2,700,000
U.K.
Acquisitions and Dispositions (Textual) [Abstract]
Number Of Dealerships Acquired	12	12
Number of franchises disposed	1	1
Number of franchises awarded	1	2
Number of franchises acquired	14	15
Number Of Dealerships Opened	1	2
Cash received in acquisition	$ 11,200,000
Net Gain (Loss) on Real Estate and Dealership Transactions		$ (300,000)