Subsequent Events (Details) - Floor Plan Facility - Line of Credit - USD ($)	Jan. 01, 2018	Aug. 04, 2017	Feb. 28, 2017
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity			$ 200,000,000
Subsequent Event
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity		$ 275,000,000
Forecast | Subsequent Event
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	$ 350,000,000