Detail of Certain Balance Sheet Accounts (Accounts and Notes Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Accounts and notes receivable
Total accounts and notes receivable	$ 203,380		$ 191,749
Less allowance for doubtful accounts	3,221		3,138
Accounts and notes receivable, net	200,159	$ 208,917	188,611
Amounts due from manufacturers [Member]
Accounts and notes receivable
Total accounts and notes receivable	107,521		109,599
Parts and service receivables [Member]
Accounts and notes receivable
Total accounts and notes receivable	52,013		39,343
Finance and insurance receivables, net [Member]
Accounts and notes receivable
Total accounts and notes receivable	31,180		25,293
Other [Member]
Accounts and notes receivable
Total accounts and notes receivable	$ 12,666		$ 17,514