Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Public Utilities, Inventory
Total inventories	$ 239.9	$ 423.0
Non-utility LPG and Natural Gas
Public Utilities, Inventory
Total inventories	140.7	283.6
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories	37.5	82.7
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories	$ 61.7	$ 56.7