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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Leases (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Accounting Policies [Abstract]          
Operating lease, right-of-use assets $ 6,792   $ 6,792   $ 3,025
Prior advance notice period for cancellation of rig contracts     45 days    
Cash payments for operating leases associated with right-of-use assets $ 700 $ 700 $ 1,900 $ 1,800  
Operating lease, weighted average remaining lease term 3 years   3 years    
Operating lease, weighted average discount rate, percent 2.70%   2.70%    
Expected future payments for contracted drilling services $ 4,300   $ 4,300