ACQUISITION (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 business
Acquisition
Number of compressed natural gas fueling businesses acquired	2
Total cash paid net of cash acquired	$ 42.6
Trillium and Pinnacle
Acquisition
Total consideration paid	49.6
Total cash paid net of cash acquired	42.6
Cash acquired	$ 7.0