Commitments and Contingencies (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended						6 Months Ended
	Jul. 31, 2011 Customer	Sep. 30, 2008 Partnership [Member] lb	Mar. 31, 2012 UGI Utilities [Member] Claims	Apr. 11, 2012 SCE & G [Member]	Sep. 22, 2006 SCE & G [Member]	Jun. 06, 2006 Key Span [Member]	Jun. 24, 2004 Key Span [Member]	Mar. 31, 2012 Environmental matters [Member]	Mar. 31, 2012 Environmental matters [Member] CPG MGP [Member]	Mar. 31, 2012 Environmental matters [Member] PNG MGP [Member]	Mar. 31, 2011 Environmental matters [Member] PNG MGP [Member]
Commitments and Contingencies [Line Items]
Environmental expenditures cap during calendar year									$ 1.8	$ 1.1
Accrual for environmental loss contingencies									16.8		20.9
Base year for determination of investigation and remediation cost								5 years
Litigating claims relating to out of state sites			3
Percentage of costs associated with sites					25.00%		50.00%
Approximate remediation cost spent by claimant					22.0		2.3
Third party claim relating to the site					26
Environmental exit cost anticipated by claimant				14			11
Environmental exit cost based on third party estimate						10
Additional environment exit cost based on claimant estimate						$ 20
Amount of propane in cylinders being sold		17
Reduced amount of propane in cylinders being sold		15
Commitments and Contingencies (Textual) [Abstract]
Number of residential customer	400