Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables
Gross receivables	$ 82,581	$ 61,408
Allowance for doubtful accounts	(2,700)	(2,920)
Receivables, net	79,881	58,488
Trade accounts receivable
Receivables
Gross receivables	13,881	4,199
Due from manufacturers
Receivables
Gross receivables	18,746	13,950
New and used vehicles
Receivables
Gross receivables	3,168	1,791
Parts, services and other
Receivables
Gross receivables	11,261	12,912
Other
Receivables
Gross receivables	7,395	1,903
Consumer services and plans
Receivables
Gross receivables	$ 28,130	$ 26,653