Annual report pursuant to Section 13 and 15(d)

Asset Retirement Obligations - Additional Information (Details)

v3.21.2
Asset Retirement Obligations - Additional Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Asset Retirement Obligation Disclosure [Abstract]      
Asset retirement obligation $ 2,788 $ 0 $ 0
Asset retirement obligation, accretion expense $ 0 $ 0 $ 0