Accrued Liabilities (Details) - Warranty reserve - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Balance at beginning of year	$ 405,000	$ 322,000
Provisions	176,000	307,000
Deductions	(151,000)	(224,000)
Balance at end of year	$ 430,000	$ 405,000