Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011
Business Segment Information
Number of reportable segments			3
Business Segment Information
Total revenues	$ 13,994	$ 14,881	$ 45,802	$ 43,166
Segment operating income (loss)	(427)	365	1,313	1,657
Unallocated amounts:
Corporate and other expenses	(1,423)	(1,217)	(4,110)	(4,416)
Amortization of intangible assets	(161)	(141)	(483)	(343)
Change in fair value of contingent acquisition consideration	(133)	281	188	639
Other income , net	1	3	9	4
Interest income (expense), net	12	(13)	(2)	(64)
Income (loss) from continuing operations before income taxes	(414)	355	1,320	1,597
Total reportable segments
Business Segment Information
Segment operating income (loss)	1,290	1,442	5,718	5,777
Roadway Sensors
Business Segment Information
Total revenues	5,081	6,598	19,485	21,234
Segment operating income (loss)	243	840	3,228	4,087
Transportation Systems
Business Segment Information
Total revenues	7,972	7,994	23,786	21,643
Segment operating income (loss)	981	654	2,559	1,742
iPerform
Business Segment Information
Total revenues	941	289	2,531	289
Segment operating income (loss)	$ 66	$ (52)	$ (69)	$ (52)