Common Stock and Equity-Based Compensation - Weighted Average Assumption Used to Determine the Fair Value of AmeriGas Performance Unit Awards and Related Compensation Costs (Details) - AmeriGas Performance Units	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free rate	2.50%	2.00%	1.50%
Expected life	3 years	3 years	3 years
Expected volatility	22.40%	21.10%	21.70%
Dividend yield	12.50%	8.20%	7.80%