Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Sep. 30, 2015	Mar. 31, 2015
Public Utilities, Inventory
Total inventories	$ 16,685	$ 51,716	$ 19,533
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories	3,786	37,510	6,260
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories	$ 12,899	$ 14,206	$ 13,273