Inventories Textual (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 ft3	Sep. 30, 2013 ft3	Dec. 31, 2012 ft3
Inventory, Net [Abstract]
Volume of gas storage inventories released under SCAAs with non-affiliates (In Cubic Feet)	9,800,000,000	11,000,000,000	9,100,000,000
Carrying value of gas storage inventories released under SCAAs with non-affiliates	$ 39,362	$ 44,366	$ 27,251
SCAAs [Member]
Public Utilities, Inventory [Line Items]
Number of storage agreements (in storage agreements)	4
SCAAs [Member] | Other current liabilities [Member]
Inventory, Net [Abstract]
Security Deposit Liability		$ 16,500	$ 16,500