Inventories, Contracts in Progress and Vehicle Floor Plan Payable (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	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	42,600,000
Floor plan assistance	$ 400,000	$ 400,000
Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Weighted average interest rate	2.60%	3.50%
London Interbank Offered Rate (LIBOR) [Member] | Automotive [Member] | Vehicle Floor Plan Facility [Member]
Inventory [Line Items]
Applicable interest rate margin	1.15%