Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]	0000086264 (http://www.sec.gov/CIK)
Period [Axis]	2013-01-01 - 2013-12-31
Supply Commitment [Axis]	Transportation Contracts [Member]
Business Acquisition [Axis]	Business Acquisition, Acquiree [Domain]
Legal Entity [Axis]	Entity [Domain]

Supply Commitment [Line Items]	Range [Axis]
	Maximum [Member]				Minimum [Member]				Range [Domain]
	Contract Tenure [Axis]				Contract Tenure [Axis]				Contract Tenure [Axis]
	Tenure Period One [Member]	Tenure Period Two [Member]	Tenure Period Three [Member]	Tenure Period Four [Member]	Tenure Period One [Member]	Tenure Period Two [Member]	Tenure Period Three [Member]	Tenure Period Four [Member]	Tenure Period One [Member]	Tenure Period Two [Member]	Tenure Period Three [Member]	Tenure Period Four [Member]	Tenure Period Five [Member]
Capacity levels (Dekatherms per day)									7,250	6,450	4,450	3,300	1,000
Demand charges (in dollars per dekatherm)	.67	.67	.67	.67	.20	.20	.20	.22					.22