Summary of Significant Accounting Policies - Refundable Tank and Cylinder Deposits and Environmental Matters (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Customer paid deposits primarily on owned tanks and cylinders	$ 243	$ 296
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Environmental Loss Contingency, Statement of Financial Position Extensible Enumeration Not Disclosed Flag [Member]