Employee Retirement Plans - Change in Pension Benefits and Other Postretirement Benefits Obligations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Net actuarial loss (gain)	$ 10.2	$ 9.4
Pension Benefit
Change in benefit obligations:
Benefit obligations — beginning of year	516.5	573.4
Service cost	9.4	11.3	9.3
Interest cost	26.1	23.8	25.1
Actuarial (gain) loss	46.8	(72.7)
Plan amendments	0	1.0
Foreign currency	(2.4)	1.5
Benefits paid	(22.8)	(21.8)
Benefit obligations — end of year	573.6	516.5	573.4
Change in plan assets:
Fair value of plan assets — beginning of year	415.3	369.9
Actual gain on plan assets	47.9	42.2
Foreign currency	(1.2)	0.8
Employer contributions	20.2	24.2
Benefits paid	(22.8)	(21.8)
Fair value of plan assets — end of year	459.4	415.3	369.9
Funded status of the plans — end of year	(114.2)	(101.2)
Assets (liabilities) recorded in the balance sheet:
Assets in excess of liabilities — included in other noncurrent assets	0	0
Unfunded liabilities — included in other current liabilities	(1.1)	(17.9)
Unfunded liabilities — included in other noncurrent liabilities	(113.1)	(83.3)
Net amount recognized	(114.2)	(101.2)
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Prior service credit	(0.1)	(0.1)
Net actuarial loss (gain)	20.8	16.7
Total	20.7	16.6
Amounts recorded in regulatory assets and liabilities (pre-tax):
Prior service cost (credit)	1.9	2.2
Net actuarial loss	107.4	91.3
Total	109.3	93.5
Other Postretirement Benefits
Change in benefit obligations:
Benefit obligations — beginning of year	19.7	24.7
Service cost	0.5	0.6	0.4
Interest cost	0.9	0.9	1.1
Actuarial (gain) loss	1.3	(3.6)
Plan amendments	0	(1.8)
Foreign currency	(0.3)	0.2
Benefits paid	(0.8)	(1.3)
Benefit obligations — end of year	21.3	19.7	24.7
Change in plan assets:
Fair value of plan assets — beginning of year	11.7	11.2
Actual gain on plan assets	1.4	1.1
Foreign currency
Employer contributions	0.5	0.7
Benefits paid	(0.8)	(1.3)
Fair value of plan assets — end of year	12.8	11.7	11.2
Funded status of the plans — end of year	(8.5)	(8.0)
Assets (liabilities) recorded in the balance sheet:
Assets in excess of liabilities — included in other noncurrent assets	4.0	3.2
Unfunded liabilities — included in other current liabilities	(0.1)	(0.4)
Unfunded liabilities — included in other noncurrent liabilities	(12.4)	(10.8)
Net amount recognized	(8.5)	(8.0)
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Prior service credit	(0.1)	(0.1)
Net actuarial loss (gain)	0.8	(0.4)
Total	0.7	(0.5)
Amounts recorded in regulatory assets and liabilities (pre-tax):
Prior service cost (credit)	(3.6)	(4.3)
Net actuarial loss	2.6	3.6
Total	$ (1.0)	$ (0.7)