Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 segment	Sep. 30, 2013
Business Segment Information
Number of reportable segments			3
Business Segments
Total revenues	$ 18,550	$ 17,027	$ 36,666	$ 34,057
Depreciation			252	402
Segment operating income (loss)	(320)	1,002	(415)	1,671
Operating segments
Business Segments
Total revenues	18,550	17,027	36,666	34,057
Segment operating income (loss)	1,893	2,436	3,850	4,690
Operating segments | Roadway Sensors
Business Segments
Total revenues	10,196	8,777	19,216	16,306
Segment operating income (loss)	2,123	1,956	3,920	3,170
Operating segments | Transportation Systems
Business Segments
Total revenues	7,284	6,898	14,949	15,156
Segment operating income (loss)	965	743	1,819	2,029
Operating segments | iPerform
Business Segments
Total revenues	1,070	1,352	2,501	2,595
Segment operating income (loss)	$ (1,195)	$ (263)	$ (1,889)	$ (509)