Employee Retirement Plans (Net periodic pension expense and other postretirement benefit costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits [Member]
Components of Net periodic pension expense and other postretirement benefit costs [Abstract]
Service cost	$ 8,063	$ 8,151
Interest cost	24,095	23,815
Other Postretirement Benefits [Member]
Components of Net periodic pension expense and other postretirement benefit costs [Abstract]
Service cost	162	217
Interest cost	665	701
UGI Utilities Employees [Member] | Pension Benefits [Member]
Components of Net periodic pension expense and other postretirement benefit costs [Abstract]
Service cost	7,025	7,176	6,980
Interest cost	22,376	22,047	21,137
Expected return on assets	(23,762)	(23,937)	(23,433)
Curtailment gain	0	0	0
Amortization of:
Prior service cost (benefit)	249	302	36
Actuarial loss	7,853	6,838	5,331
Net benefit cost (income)	13,741	12,426	10,051
Change in associated regulatory liabilities	0	0	0
Benefit cost (income) after change in regulatory liabilities	13,741	12,426	10,051
UGI Utilities Employees [Member] | Other Postretirement Benefits [Member]
Components of Net periodic pension expense and other postretirement benefit costs [Abstract]
Service cost	152	202	175
Interest cost	639	678	752
Expected return on assets	(481)	(523)	(508)
Curtailment gain	0	(3,245)	0
Amortization of:
Prior service cost (benefit)	(422)	(694)	(406)
Actuarial loss	355	427	231
Net benefit cost (income)	243	(3,155)	244
Change in associated regulatory liabilities	3,188	3,138	3,137
Benefit cost (income) after change in regulatory liabilities	$ 3,431	$ (17)	$ 3,381