Regulatory Assets and Liabilities and Regulatory Matters Textual (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended			12 Months Ended		12 Months Ended		3 Months Ended	0 Months Ended
	Oct. 21, 2010	Sep. 30, 2012	Sep. 30, 2011	Dec. 01, 2010 mi	Sep. 30, 2012 UGI Central Penn Gas Inc [Member]	Jan. 14, 2011 UGI Central Penn Gas Inc [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]	Mar. 31, 2011 UGI Storage Company [Member] UGI Central Penn Gas Inc [Member]	Oct. 03, 2012 Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Violation	Feb. 09, 2011 Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Persons
Schedule of Regulatory Assets and Liabilities [Line Items]
Average remaining depreciable lives of the associated property							1 year	50 years
Unrealized gains (losses) on derivative financial instruments contracts		$ 5,303	$ (3,081)
Fair value of electric utility electricity supply contracts		9,207	8,655
Minimum period to recover costs related to other regulatory assets		1 year
Maximum period to recover costs related to other regulatory assets		5 years
Maximum percentage of incremental operating margin traditional ratemaking (as a percent)		5.00%
Number of years to be eligible for a distribution system improvement charge a utility must have filed a general rate filing		5 years
Deaths from natural gas explosion (in persons)											5
Pending claims (in claims)										6
Damages paid										386
Site Contingency, Accelerated Time Frame Replacing Remainder of Cast-Iron Mains										14 years
Loss Contingency, Agreement to not Seek Recovery of Related Annual Cost of Capital Return Requirements Period										24 months
Loss Contingency, Agreement Permitted To Retain Current Timeframe for Replacing The Remainder of Their Bare Steel Mains										30 years
Request to increase base operating revenues to fund system improvements and operations						16,500
Additional base rate revenue using for increased distribution rates per settlement agreement					8,000
Base rate revenue increase for use in CPG's Energy and Efficiency Program					900
Reversal of Previous Increase in Base Rate Revenue					900
Agreement To Charge Customers, Period	3 years
Net book value of the storage facility assets			10,949
Deferred Tax Assets, Regulatory Assets and Liabilities			308	180
Storage agreement, term									1 year
Approval of the transfer length of natural gas pipeline (in miles)				9.0
Net book value of the Auburn line				$ 1,109