Summary of Significant Accounting Policies - Asset Retirement Obligations (Details) - USD ($) $ in Thousands |
1 Months Ended | 12 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
Asset Retirement Obligations | ||||
Asset retirement obligation, period increase (decrease) | $ 800 | |||
Asset retirement obligations | $ 2,284 | $ 2,825 | ||
Estimated asset retirement obligations | 3,300 | 3,300 | ||
Accretion reserve | $ (389) | |||
Accretion expense | 215 | $ 202 | ||
Specialty rental costs | ||||
Asset Retirement Obligations | ||||
Accretion expense | $ 200 | $ 200 |