Common Stock and Equity-Based Compensation - Common Stock Share Activity (Details) - Common Stock - shares	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Common Stock Share Activity
Beginning balance - shares Issued/Treasury (in shares)	209,514,044	209,304,129	174,142,997	173,987,691
Beginning balance - shares Outstanding (in shares)	209,004,789	173,748,975	173,143,737
Issued:
Employee and director plans - shares Issued/Treasury (in shares)	209,915	548,285	155,306
Employee and director plans - shares Outstanding (in shares)	389,965	979,132	1,960,018
AmeriGas Merger -Issued (in shares)		34,612,847
AmeriGas Merger - Outstanding (in shares)		34,612,847
Sale of reacquired common stock - Outstanding (in shares)		15,759
Reacquired common stock, employee and director plans - Outstanding (in shares)	(90,316)	(51,924)	(154,780)
Ending balance - shares Issued/Treasury (in shares)	209,514,044	209,304,129	174,142,997	173,987,691
Ending balance - shares Outstanding (in shares)	208,354,438	209,004,789	173,748,975
Treasury
Common Stock Share Activity
Beginning balance - shares Issued/Treasury (in shares)	1,159,606	299,340	394,022	843,954
Issued:
Employee and director plans - shares Issued/Treasury (in shares)	180,050	430,847	1,804,712
AmeriGas Merger -Issued (in shares)		0
Sale of reacquired common stock - Treasury (in shares)		15,759
Repurchases of common stock - Treasury (in shares)	(950,000)	(300,000)	(1,200,000)
Reacquired common stock, employee and director plans - Treasury (in shares)	(90,316)	(51,924)	(154,780)
Ending balance - shares Issued/Treasury (in shares)	1,159,606	299,340	394,022	843,954