Sale of Vehicle Sensors (Details) (Vehicle Sensors segment, USD $)	1 Months Ended	3 Months Ended
	Jul. 31, 2011	Jun. 30, 2012
Vehicle Sensors segment
Sale of Vehicle Sensors
Additional cash consideration, percentage of revenue associated with royalties	0.85
Additional cash consideration, percentage on excess of revenue over projected revenue	0.30
Additional cash consideration, period for which revenue generated exceeds projected revenue	2 years
Gain on the sale related to performance and royalty-related earn-outs achieved, net of tax		$ 87,000