Summary of Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Oct. 13, 2016	Sep. 19, 2008
Deferred Revenue Arrangement [Line Items]
Inventory reserve	$ 39,000	$ 67,000
Revenue recognition, licensing contract term (years)	5 years
Advertising expense	$ 404,000	$ 401,000
Minimum
Deferred Revenue Arrangement [Line Items]
Revenue recognition, royalty earned on licensing agreement (percent)	4.00%
Maximum
Deferred Revenue Arrangement [Line Items]
Revenue recognition, royalty earned on licensing agreement (percent)	6.00%
Buildings | Minimum
Deferred Revenue Arrangement [Line Items]
Useful life	10 years
Buildings | Maximum
Deferred Revenue Arrangement [Line Items]
Useful life	40 years
Trucks and automotive equipment | Minimum
Deferred Revenue Arrangement [Line Items]
Useful life	3 years
Trucks and automotive equipment | Maximum
Deferred Revenue Arrangement [Line Items]
Useful life	10 years
Shop machinery and equipment | Minimum
Deferred Revenue Arrangement [Line Items]
Useful life	3 years
Shop machinery and equipment | Maximum
Deferred Revenue Arrangement [Line Items]
Useful life	10 years
Land improvements | Minimum
Deferred Revenue Arrangement [Line Items]
Useful life	10 years
Land improvements | Maximum
Deferred Revenue Arrangement [Line Items]
Useful life	15 years
Office equipment | Minimum
Deferred Revenue Arrangement [Line Items]
Useful life	3 years
Office equipment | Maximum
Deferred Revenue Arrangement [Line Items]
Useful life	10 years
Stock options
Deferred Revenue Arrangement [Line Items]
Vesting period	3 years
Available shares for grant (up to) (in shares)			400,000	500,000
Restricted Stock Units
Deferred Revenue Arrangement [Line Items]
Vesting period	3 years
Granted (in shares)	72,000	103,000