Inventories, Contracts in Progress and Vehicle Floor Plan Payable (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Weighted average interest rate	5.10%	5.10%
Vehicle floor plan payable		$ 25,800,000
Automotive [Member]
Inventory [Line Items]
Borrowing capacity	$ 50,000,000
Vehicle floor plan payable	26,000,000.0
Floor plan assistance	$ 2,100,000	$ 1,800,000
Vehicle Floor Plan Facility [Member] | Automotive [Member]
Inventory [Line Items]
Weighted average interest rate	1.70%	3.30%
Vehicle Floor Plan Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Automotive [Member]
Inventory [Line Items]
Applicable interest rate margin	1.15%