Employee Retirement Plans - Fair Value of Pension Plan and VEBA Trust Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	$ 430,789	$ 442,465	$ 398,171
Pension Benefits | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	242,037	245,857
Pension Benefits | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	147,266	152,613
Pension Benefits | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	40,625	41,417
Pension Benefits | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	10,727	9,325
Pension Benefits | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	43,419	42,502
Pension Benefits | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	43,906	49,935
Pension Benefits | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	144,846	146,673
Pension Benefits | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,776	140,949
Pension Benefits | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	4,070	5,724
Pension Benefits | Level 1
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	426,719	436,741
Pension Benefits | Level 1 | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	242,037	245,857
Pension Benefits | Level 1 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	147,266	152,613
Pension Benefits | Level 1 | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	40,625	41,417
Pension Benefits | Level 1 | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	10,727	9,325
Pension Benefits | Level 1 | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	43,419	42,502
Pension Benefits | Level 1 | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	43,906	49,935
Pension Benefits | Level 1 | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,776	140,949
Pension Benefits | Level 1 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,776	140,949
Pension Benefits | Level 1 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	4,070	5,724
Pension Benefits | Level 2 | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	4,070	5,724
Pension Benefits | Level 2 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 2 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	4,070	5,724
Pension Benefits | Level 3
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
Pension Benefits | Level 3 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	12,523	12,848
VEBA Trust | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	8,434	8,719
VEBA Trust | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	3,832	3,727
VEBA Trust | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	257	402
VEBA Trust | Level 1
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	12,266	12,446
VEBA Trust | Level 1 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	8,434	8,719
VEBA Trust | Level 1 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	3,832	3,727
VEBA Trust | Level 1 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 2
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	257	402
VEBA Trust | Level 2 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 2 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 2 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	257	402
VEBA Trust | Level 3
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 3 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 3 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	0	0
VEBA Trust | Level 3 | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	$ 0	$ 0