Business Segments, Significant Customer and Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014 segment	Mar. 31, 2013	Mar. 31, 2012
Business Segments, Significant Customer and Geographic Information
Number of reportable segments									3
Business Segments
Revenues	$ 17,623	$ 16,548	$ 17,027	$ 17,030	$ 15,883	$ 13,994	$ 15,504	$ 16,304	$ 68,228	$ 61,685	$ 58,406
Depreciation									768	901	907
Segment income (loss)									2,024	1,634	2,017
Transportation Systems | Advanced traveler information systems
Business Segments
Number of advanced traveler information systems									511
Operating segments
Business Segments
Depreciation									487	603	592
Segment income (loss)									7,579	7,447	7,597
Operating segments | Roadway Sensors
Business Segments
Revenues									31,769	26,002	27,679
Depreciation									208	221	194
Segment income (loss)									5,791	4,119	4,813
Operating segments | Transportation Systems
Business Segments
Revenues									30,524	30,010	29,792
Depreciation									161	362	393
Segment income (loss)									3,363	3,561	3,151
Operating segments | iPerform
Business Segments
Revenues									5,953	5,673	935
Depreciation									118	20	5
Segment income (loss)									$ (1,575)	$ (233)	$ (367)