Inventories, Contracts in Progress and Vehicle Floor Plan Payable (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Inventory [Line Items]
Weighted average interest rate	5.00%	5.10%	5.10%	5.10%
Vehicle floor plan payable					$ 25,800,000
Automotive [Member]
Inventory [Line Items]
Borrowing capacity	$ 50,000,000		$ 50,000,000
Vehicle floor plan payable	23,800,000		23,800,000
Floor plan assistance	$ 600,000	$ 400,000	$ 1,500,000	$ 1,600,000
Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Weighted average interest rate	1.20%	3.40%	1.90%	3.40%
London Interbank Offered Rate (LIBOR) [Member] | Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Applicable interest rate margin			1.15%