Employee Retirement Plans - Fair Value of Pension Plan and VEBA Trust Assets (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Pension Benefits
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	$ 442,465	$ 398,171	$ 351,543
Pension Benefits | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	245,857	228,853
Pension Benefits | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	152,613	141,774
Pension Benefits | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	41,417	54,528
Pension Benefits | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	9,325
Pension Benefits | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	42,502	32,551
Pension Benefits | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	49,935	44,452
Pension Benefits | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	146,673	124,866
Pension Benefits | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,949	120,906
Pension Benefits | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	5,724	3,960
Pension Benefits | Level 1
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	436,741	394,211
Pension Benefits | Level 1 | Domestic Equity Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	245,857	228,853
Pension Benefits | Level 1 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	152,613	141,774
Pension Benefits | Level 1 | Small and Midcap Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	41,417	54,528
Pension Benefits | Level 1 | Smallcap Common Stocks
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	9,325
Pension Benefits | Level 1 | UGI Corporation Common Stock
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	42,502	32,551
Pension Benefits | Level 1 | International Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	49,935	44,452
Pension Benefits | Level 1 | Fixed Income Investments
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,949	120,906
Pension Benefits | Level 1 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	140,949	120,906
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	5,724	3,960
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
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	5,724	3,960
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	5,724	3,960
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
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	12,848	11,723
VEBA Trust | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	8,719	7,693
VEBA Trust | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	3,727	3,794
VEBA Trust | Cash Equivalents
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	402	236
VEBA Trust | Level 1
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	12,446	11,487
VEBA Trust | Level 1 | S&P 500 Index Equity Mutual Funds
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	8,719	7,693
VEBA Trust | Level 1 | Bond Index Mutual Fund
Fair Value of Pension Plan Assets
Fair Value of Plan Assets	3,727	3,794
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	402	236
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	402	236
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