Revenue Concentrations, Significant Customers, and Geographic Areas (Narrative) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Revenues	$ 18,063,000	$ 16,683,000	$ 15,854,000	$ 14,120,000	$ 13,176,000	$ 11,828,000	$ 16,409,000	$ 11,920,000	$ 64,720,000	$ 53,333,000
Revenue, export sales percentage									72.00%	71.00%
Accounts receivable	15,859,000				$ 10,772,000				$ 15,859,000	$ 10,772,000
MRS based sensors [Member]
Revenue, Major Customer [Line Items]
Revenues									7,900,000	4,400,000
MRS based systems [Member]
Revenue, Major Customer [Line Items]
Revenues									13,300,000	$ 10,000,000.0
Significant Customer A [Member]
Revenue, Major Customer [Line Items]
Accounts receivable	922,000								922,000
Significant Customer B [Member]
Revenue, Major Customer [Line Items]
Accounts receivable	$ 1,400,000								$ 1,400,000