Annual report pursuant to Section 13 and 15(d)

Leases - Changes in Carrying Amount of AROs (Detail)

v3.20.4
Leases - Changes in Carrying Amount of AROs (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]    
Balance at beginning of year $ 1,365 $ 344
Liabilities incurred in the current period 0 949
Accretion of asset retirement obligations 125 72
Balance at end of year $ 1,490 $ 1,365