XML 41 R29.htm IDEA: XBRL DOCUMENT v3.21.2
BASIS OF PRESENTATION OF UNAUDITED INTERIM CONDENSED CONSOLIDATED FINANCIAL STATEMENTS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Depreciation (Details) - USD ($)
$ in Millions
3 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Accounting Policies [Abstract]    
Depreciation expense, asset retirement obligation $ 0.3 $ 1.3