Supplementary Financial Information - Inventories , Property and Equipment (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Inventories
Materials and supplies	$ 887,000	$ 1,754,000
Work in process	298,000	217,000
Finished goods	1,065,000	1,182,000
Total inventories	2,250,000	3,153,000
Property and Equipment, net
Accumulated depreciation	(7,508,000)	(6,854,000)
Net	2,064,000	2,139,000
Depreciation expense	729,000	649,000	$ 525,000
Equipment
Property and Equipment, net
Gross	7,078,000	6,530,000
Leasehold improvements
Property and Equipment, net
Gross	2,494,000	2,463,000
Cost of revenues
Property and Equipment, net
Depreciation expense	269,000	252,000	225,000
Operating expenses
Property and Equipment, net
Depreciation expense	$ 460,000	$ 397,000	$ 300,000