Impairment - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) $ / bbl	Mar. 31, 2019 USD ($)
Impairments [Line Items]
Impairment charge, pre-tax	$ 2,126	$ 0
Bakken
Impairments [Line Items]
Right-of-use assets, impairment charge, pre-tax	21
Right-of-use assets, impairment charge, after income taxes	20
Oil and Gas Properties
Impairments [Line Items]
Fair value of estimated impairment charges determined using internal projected discounted cash flows	$ 1,050
Fair value of estimated impairment charges discount rate	10.00%
Weighted average crude oil benchmark price for impaired assets | $ / bbl	48.82
Oil and Gas Properties | West Texas Intermediate
Impairments [Line Items]
Impairment charge, future flat price | $ / bbl	50
Oil and Gas Properties | Brent
Impairments [Line Items]
Impairment charge, future flat price | $ / bbl	55
Oil and Gas Properties | North Malay Basin Field | Malaysia
Impairments [Line Items]
Impairment charge, pre-tax	$ 755
Impairment charge, after income taxes	755
Oil and Gas Properties | South Arne Field | Denmark
Impairments [Line Items]
Impairment charge, pre-tax	670
Impairment charge, after income taxes	594
Oil and Gas Properties | Stampede Field | Gulf of Mexico
Impairments [Line Items]
Impairment charge, pre-tax	410
Impairment charge, after income taxes	410
Oil and Gas Properties | Tubular Bells Field
Impairments [Line Items]
Impairment charge, pre-tax	270
Impairment charge, after income taxes	$ 270