Sale of Vehicle Sensors (Details) (USD $)	3 Months Ended	6 Months Ended			0 Months Ended			6 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Jul. 29, 2011 segment	Oct. 31, 2012 Vehicle Sensors segment	Jul. 29, 2011 Vehicle Sensors segment	Jul. 25, 2011 Vehicle Sensors segment	Sep. 30, 2014 Vehicle Sensors segment	Sep. 30, 2013 Vehicle Sensors segment	Jul. 25, 2011 Vehicle Sensors segment
Sale of Vehicle Sensors
Aggregate proceeds received on sale							$ 14,000,000
Holdback amount										2,000,000
Additional cash consideration, percentage of revenue associated with royalties						85.00%
Additional cash consideration, percentage on excess of revenue over projected revenue						30.00%
Additional cash consideration, period for which revenue generated exceeds target revenue						2 years
Amount of earn-outs in connection with royalty								1,200,000
Number of discontinued operations business segments				1
Cash received pursuant to resolution of the holdback provision					1,700,000
Cash proceeds from sale of assets		98,000						14,900,000
Sale of Vehicle Sensors, additional disclosures
Gain on sale of discontinued operation, net of tax	$ 46,000	$ 95,000	$ 30,000					$ 95,000	$ 30,000