Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Public Utilities, Inventory
Total inventories	$ 51,716	$ 95,219
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories	37,510	82,664
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories	$ 14,206	$ 12,555