Business Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2014 segment	Jun. 30, 2013
Business Segment Information
Number of reportable segments	3
Business Segments
Total revenues	$ 18,116	$ 17,030
Depreciation	127	211
Segment operating income (loss)	(95)	669
Operating segments
Business Segments
Total revenues	18,116	17,030
Segment operating income (loss)	1,957	2,254
Operating segments | Roadway Sensors
Business Segments
Total revenues	9,020	7,529
Segment operating income (loss)	1,797	1,214
Operating segments | Transportation Systems
Business Segments
Total revenues	7,665	8,258
Segment operating income (loss)	854	1,286
Operating segments | iPerform
Business Segments
Total revenues	1,431	1,243
Segment operating income (loss)	$ (694)	$ (246)