Regulation and Rates (Details) (USD $)		0 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended		1 Months Ended	0 Months Ended
	Dec. 31, 2011	Dec. 13, 2010 Panhandle [Member]	Dec. 31, 2011 Panhandle [Member]	Dec. 31, 2011 Panhandle [Member]	Feb. 10, 2010 Missouri Gas Energy [Member]	Apr. 02, 2009 Missouri Gas Energy [Member]	Feb. 28, 2010 Missouri Gas Energy [Member]	Jul. 13, 2011 New England Gas Company [Member]	Nov. 13, 2009 New England Gas Company [Member]	Sep. 15, 2008 New England Gas Company [Member]
Regulated Operations [Line Items]
Amount Of Regulatory Costs Not Yet Approved	$ 20,800,000
Surcharge Recovery Period		21.4		4
Base Rate Increase						32,400,000
Refunds Reserved			17,700,000
Costs incurred to be recovered via surcharge				44,000,000
Revenue Increase Authorized					16,200,000
Percent Residential Small General Service Customers							99
Percent Residential Small General Service Net Operating Revenues							91			4,000,000
Earnings Share Adjustment Recovery									1,700,000
Remand Recovery								4,100,000
Construction Cost With Capitalized Interest				440,000,000
Construction Project Period				20
Percentage HCAs Assessments Required				93.00%
Estimate Required Modifications And Inspections Minimum				20,000,000
Estimate Required Modifications And Inspections Maximum				$ 30,000,000