Employee Retirement Plans - Change in Pension Benefits and Other Postretirement Benefits Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Net actuarial loss	$ 10.1	$ 10.2
Pension Benefit
Change in benefit obligations:
Benefit obligations — beginning of year	573.6	516.5
Service cost	10.0	9.4	$ 11.3
Interest cost	25.5	26.1	23.8
Actuarial loss (gain)	14.4	46.8
Plan amendments	(0.6)
Curtailment	(0.8)	0.0
Totalgaz acquisition	21.3	0.0
Foreign currency	(4.4)	(2.4)
Benefits paid	(24.3)	(22.8)
Benefit obligations — end of year	614.7	573.6	516.5
Change in plan assets:
Fair value of plan assets — beginning of year	459.4	415.3
Actual gain (loss) on plan assets	1.1	47.9
Foreign currency	(0.4)	(1.2)
Employer contributions	11.9	20.2
Totalgaz acquisition	6.1
Benefits paid	(24.3)	(22.8)
Fair value of plan assets — end of year	453.8	459.4	415.3
Funded status of the plans — end of year	(160.9)	(114.2)
Assets (liabilities) recorded in the balance sheet:
Assets in excess of liabilities — included in other noncurrent assets	0.0	0.0
Unfunded liabilities — included in other current liabilities		(1.1)
Unfunded liabilities — included in other noncurrent liabilities	(160.9)	(113.1)
Net amount recognized	(160.9)	(114.2)
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Prior service credit	(0.6)	(0.1)
Net actuarial loss	22.5	20.8
Total	21.9	20.7
Amounts recorded in regulatory assets and liabilities (pre-tax):
Prior service cost (credit)	1.6	1.9
Net actuarial loss	138.4	107.4
Total	140.0	109.3
Other Postretirement Benefits
Change in benefit obligations:
Benefit obligations — beginning of year	21.3	19.7
Service cost	0.7	0.5	0.6
Interest cost	0.8	0.9	0.9
Actuarial loss (gain)	(2.7)	1.3
Plan amendments	0.0
Curtailment	0.0	0.0
Totalgaz acquisition	6.8
Foreign currency	(0.7)	(0.3)
Benefits paid	(0.8)	(0.8)
Benefit obligations — end of year	25.4	21.3	19.7
Change in plan assets:
Fair value of plan assets — beginning of year	12.8	11.7
Actual gain (loss) on plan assets	(0.1)	1.4
Employer contributions	0.6	0.5
Benefits paid	(0.8)	(0.8)
Fair value of plan assets — end of year	12.5	12.8	$ 11.7
Funded status of the plans — end of year	(12.9)	(8.5)
Assets (liabilities) recorded in the balance sheet:
Assets in excess of liabilities — included in other noncurrent assets	4.0	4.0
Unfunded liabilities — included in other current liabilities		(0.1)
Unfunded liabilities — included in other noncurrent liabilities	(16.9)	(12.4)
Net amount recognized	(12.9)	(8.5)
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Prior service credit	(0.1)	(0.1)
Net actuarial loss	0.7	0.8
Total	0.6	0.7
Amounts recorded in regulatory assets and liabilities (pre-tax):
Prior service cost (credit)	(2.9)	(3.6)
Net actuarial loss	2.3	2.6
Total	$ (0.6)	$ (1.0)