Employee Retirement Plans - Components of Net Periodic Pension Expense and Other Postretirement Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Defined Benefit Plan Disclosure
Service cost	$ 7,772	$ 7,863
Interest cost	25,733	24,656
Other Postretirement Benefits
Defined Benefit Plan Disclosure
Service cost	198	220
Interest cost	483	511
UGI Utilities Employees | Pension Benefits
Defined Benefit Plan Disclosure
Service cost	6,927	6,962	$ 6,492
Interest cost	23,270	22,511	22,885
Expected return on assets	(28,668)	(28,898)	(26,599)
Amortization of:
Prior service cost (benefit)	348	348	348
Actuarial loss	9,571	8,793	6,642
Net benefit cost (income)	11,448	9,716	9,768
Change in associated regulatory liabilities	0	0	0
Net benefit cost after change in regulatory liabilities	11,448	9,716	9,768
UGI Utilities Employees | Other Postretirement Benefits
Defined Benefit Plan Disclosure
Service cost	183	202	162
Interest cost	465	479	488
Expected return on assets	(596)	(612)	(557)
Amortization of:
Prior service cost (benefit)	(641)	(641)	(641)
Actuarial loss	98	122	116
Net benefit cost (income)	(491)	(450)	(432)
Change in associated regulatory liabilities	971	3,740	3,704
Net benefit cost after change in regulatory liabilities	$ 480	$ 3,290	$ 3,272