Inventories - Schedule of Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014	Mar. 31, 2014
Public Utilities, Inventory
Total inventories	$ 19,533	$ 95,219	$ 20,629
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories	6,260	82,664	7,490
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories	$ 13,273	$ 12,555	$ 13,139