XML 51 R40.htm IDEA: XBRL DOCUMENT v3.8.0.1
Disclosures About Fair Value Measurements (Narrative) (Detail)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2016
USD ($)
Sep. 30, 2017
Dec. 31, 2024
$ / bbl
$ / MMBTU
Dec. 31, 2021
$ / bbl
Dec. 31, 2020
$ / MMBTU
Dec. 31, 2017
$ / bbl
$ / MMBTU
Disclosure Fair Value Narrative [Abstract]            
Management Estimate of Future Oil Price | $ / bbl     52.01 50.77   52.29
Management Estimate of Future Natural Gas Price | $ / MMBTU     2.88   2.85 3.14
Annual discount rate   10.00%        
Carrying Amount $ 3,438          
Impairment Expense $ 1,525