Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	3 Months Ended	9 Months Ended		9 Months Ended						9 Months Ended			9 Months Ended
	Jun. 30, 2012 Environmental Issue [Member]	Jun. 30, 2012 Environmental Issue [Member] PNG MGP [Member]	Jun. 30, 2012 Environmental Remediation Expense [Member] CPG MGP [Member]	Mar. 31, 2012 Environmental Remediation Expense [Member] CPG MGP [Member]	Jun. 30, 2012 Environmental Remediation Expense [Member] PNG MGP [Member]	Mar. 31, 2011 Environmental Remediation Expense [Member] PNG MGP [Member]	Jun. 06, 2006 Key Span [Member]	Jun. 24, 2004 Key Span [Member]	May 22, 2009 Yankee Gas Services Company and Connecticut Light and Power Company [Member] MPG Operations [Member] Site	Sep. 11, 2006 Yankee Gas Services Company and Connecticut Light and Power Company [Member] MPG Operations [Member] Site	Jun. 30, 2012 Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Claims	Feb. 09, 2011 Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Persons	Sep. 22, 2006 Closed Litigation [Member] SCE and G [Member]	Jun. 30, 2012 Pending Litigation [Member] Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Decedent Claims	Jun. 30, 2012 Minimum [Member] Allentown, Pennsylvania Natural Gas Explosion [Member] Damage from Natural Gas Explosion [Member] Claims
Commitments and Contingencies [Line Items]
Environmental expenditures cap during calendar year			$ 1,800		$ 1,100
Option to termination agreement by either party effective at end of any two-year period beginning with the original effective date in March 2004 (in years)		2 years
Accrual for environmental loss contingencies				15,820		20,121
Base year for determination of investigation and remediation cost (in years)	5 years
Alleged Percentage of Liability (as a percent)								50.00%					25.00%
Approximate remediation cost spent by claimant								2,300					22,000
Approximate third party claim relating to the site													26,000
Environmental exit cost anticipated by claimant								11,000					14,000
Environmental exit cost based on third party estimate							10,000
Additional environment exit cost based on claimant estimate							20,000
Number of sites owned by claimant seeking contributions for past and future remediation costs (in sites)										13
Number of sites claimant withdrew from claims (in sites)									3
Number of sites UGI Utilities acknowledged it operated (in sites)									1
Number of sites dismissed by court (in sites)									9
Deaths from natural gas explosion (in persons)												5
Property claims (in claims)															100
Claims settled and dismissed (in claims)											3
Percentage of property claims settled to date (as a percent)											85.00%
Pending claims (in claims)														1
Pending claims, number of decedents, in which plaintiffs seeking compensatory and damages (in decendents)														2
Liability insurance deductible											$ 500