Detail of Certain Balance Sheet Accounts (Accounts and Notes Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts and notes receivable
Total accounts and notes receivable	$ 126,361	$ 112,873
Less allowance for doubtful accounts	2,985	1,645
Accounts and notes receivable, net	123,376	111,228
Amounts due from manufacturers [Member]
Accounts and notes receivable
Total accounts and notes receivable	68,591	64,039
Parts and service receivables [Member]
Accounts and notes receivable
Total accounts and notes receivable	31,943	17,879
Finance and insurance receivables, net [Member]
Accounts and notes receivable
Total accounts and notes receivable	16,545	16,060
Other [Member]
Accounts and notes receivable
Total accounts and notes receivable	$ 9,282	$ 14,895