Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2012
Minimum [Member] | Propane distribution mains [Member]
Useful Life of Assets	10 years
Minimum [Member] | Propane bulk plants and tanks [Member]
Useful Life of Assets	7 years
Minimum [Member] | Liquified petroleum gas equipment [Member]
Useful Life of Assets	5 years
Minimum [Member] | Meters and meter installations [Member]
Useful Life of Assets	5 years
Minimum [Member] | Measuring and regulating station equipment [Member]
Useful Life of Assets	5 years
Minimum [Member] | Office furniture and equipment [Member]
Useful Life of Assets	3 years
Minimum [Member] | Transportation equipment [Member]
Useful Life of Assets	3 years
Minimum [Member] | Structures and improvements [Member]
Useful Life of Assets	3 years
Maximum [Member] | Propane distribution mains [Member]
Useful Life of Assets	37 years
Maximum [Member] | Propane bulk plants and tanks [Member]
Useful Life of Assets	40 years
Maximum [Member] | Liquified petroleum gas equipment [Member]
Useful Life of Assets	40 years
Maximum [Member] | Meters and meter installations [Member]
Useful Life of Assets	33 years
Maximum [Member] | Measuring and regulating station equipment [Member]
Useful Life of Assets	37 years
Maximum [Member] | Office furniture and equipment [Member]
Useful Life of Assets	10 years
Maximum [Member] | Transportation equipment [Member]
Useful Life of Assets	20 years
Maximum [Member] | Structures and improvements [Member]
Useful Life of Assets	45 years
Maximum [Member] | Other equipment [Member]
Useful Life of Assets	Various