Partnership Acquisition of Heritage Propane (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Jun. 30, 2012
Liabilities assumed:
Total	2,604.8
Heritage Propane [Member]
Assets acquired:
Current assets	280.3
Property, plant & equipment	890.5
Customer relationships (estimated useful life of 15 years)	418.9
Trademarks and tradenames	144.2
Goodwill	1,167.5
Other assets	10.4
Total assets acquired	2,911.8
Liabilities assumed:
Current liabilities	(223.5)
Long-term debt	(61.6)
Other noncurrent liabilities	(21.9)
Total liabilities assumed	(307.0)
Customer Relationships [Member] | Heritage Propane [Member]
Finite Lived Intangible Asset Useful Life
Estimated useful life (in years)	15 years