Segment Information (Continuing Operating Segments) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 segment	Dec. 31, 2011
Net revenues	$ 6,498,000	$ 6,115,000
Sales in foreign countries	809,000	633,000
Interest income	4,000	6,000
Depreciation expense	71,000	57,000
Capital purchases	196,000	82,000
Total assets	13,338,000	11,928,000
Income before income taxes	1,642,000	809,000
Number of Reportable Segments	2
Production Monitoring [Member]
Net revenues	6,498,000	6,115,000
Sales in foreign countries	809,000	633,000
Interest income	1,000	2,000
Depreciation expense	71,000	57,000
Capital purchases	196,000	82,000
Total assets	3,016,000	2,488,000
Income before income taxes	845,000	736,000
ESI Investment Company [Member]
Net revenues	0	0
Sales in foreign countries	0	0
Interest income	3,000	4,000
Depreciation expense	0	0
Capital purchases	0	0
Total assets	10,322,000	9,440,000
Income before income taxes	$ 797,000	$ 73,000