Income Taxes - Deferred Tax Liabilities (Assets) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Excess book basis over tax basis of property, plant and equipment	$ 675.7	$ 626.9
Investment in AmeriGas Partners	325.1	313.0
Intangible assets and goodwill	53.0	65.1
Utility regulatory assets	110.0	101.6
Foreign currency translation adjustment	0	9.5
Other	3.5	2.7
Gross deferred tax liabilities	1,167.3	1,118.8
Pension plan liabilities	(40.6)	(36.2)
Employee-related benefits	(48.8)	(47.9)
Operating loss carryforwards	(27.9)	(32.1)
Foreign tax credit carryforwards	(47.8)	(81.8)
Utility regulatory liabilities	(14.8)	(15.5)
Foreign currency translation adjustment	(14.1)	0
Derivative instruments	(11.0)	(15.0)
Other	(13.0)	(20.5)
Gross deferred tax assets	(218.0)	(249.0)
Deferred tax assets valuation allowance	59.2	97.6
Net deferred tax liabilities	$ 1,008.5	$ 967.4