Detail of Certain Balance Sheet Accounts (Accounts and Notes Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts and notes receivable
Total accounts and notes receivable	$ 141,047	$ 154,971
Less allowance for doubtful accounts	3,674	3,641
Accounts and notes receivable, net	137,373	151,330
Amounts due from manufacturers [Member]
Accounts and notes receivable
Total accounts and notes receivable	79,044	86,062
Parts and service receivables [Member]
Accounts and notes receivable
Total accounts and notes receivable	33,061	35,034
Finance and insurance receivables, net [Member]
Accounts and notes receivable
Total accounts and notes receivable	19,161	20,898
Other [Member]
Accounts and notes receivable
Total accounts and notes receivable	$ 9,781	$ 12,977