Inventories, Contracts in Progress and Vehicle Floor Plan Payable (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Inventory [Line Items]
Weighted average interest rate	5.10%	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	29,100,000		29,100,000
Floor plan assistance	$ 500,000	$ 800,000	$ 900,000	$ 1,200,000
Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Weighted average interest rate	1.60%	3.40%	2.20%	3.50%
London Interbank Offered Rate (LIBOR) [Member] | Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Applicable interest rate margin			1.15%