Inventories - Schedule of Inventories (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Public Utilities, Inventory
Total inventories	$ 423.0	$ 365.5
Non-utility LPG and Natural Gas
Public Utilities, Inventory
Total inventories	283.6	230.0
Gas Utility Natural Gas
Public Utilities, Inventory
Total inventories	82.7	78.9
Materials, Supplies and Other
Public Utilities, Inventory
Total inventories	$ 56.7	$ 56.6