Revenues - Revenues from Contracts with Customers by Product Type and Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Assets	$ 19,715	$ 21,410	$ 20,245
Revenues from contracts with customers	1,024	1,200
Receivables from contract with customer	477		$ 837
United States E&P
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	970	1,062
United States E&P | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	348	389
United States E&P | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	348	394
United States E&P | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	134	144
United States E&P | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	80	78
United States E&P | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	60	57
United States E&P | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	828	859
United States E&P | Crude oil and condensate | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	307	318
United States E&P | Crude oil and condensate | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	330	372
United States E&P | Crude oil and condensate | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	84	77
United States E&P | Crude oil and condensate | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	74	64
United States E&P | Crude oil and condensate | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	33	28
United States E&P | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	52	77
United States E&P | Natural gas liquids | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	16	35
United States E&P | Natural gas liquids | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10	10
United States E&P | Natural gas liquids | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	21	22
United States E&P | Natural gas liquids | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	8
United States E&P | Natural gas liquids | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2	2
United States E&P | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	66	103
United States E&P | Natural gas | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	23	34
United States E&P | Natural gas | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	12
United States E&P | Natural gas | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	29	45
United States E&P | Natural gas | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	6
United States E&P | Natural gas | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3	6
United States E&P | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	24	23
United States E&P | Other | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2	2
United States E&P | Other | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
United States E&P | Other | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
United States E&P | Other | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
United States E&P | Other | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22	21
International E&P
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		138
International E&P | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	54	55
International E&P | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		73
International E&P | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		10
International E&P | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		113
International E&P | Crude oil and condensate | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	45	47
International E&P | Crude oil and condensate | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		56
International E&P | Crude oil and condensate | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		10
International E&P | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		2
International E&P | Natural gas liquids | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	1
International E&P | Natural gas liquids | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		1
International E&P | Natural gas liquids | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
International E&P | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		15
International E&P | Natural gas | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	7
International E&P | Natural gas | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		8
International E&P | Natural gas | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
International E&P | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		8
International E&P | Other | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
International E&P | Other | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		8
International E&P | Other | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
Operating Segments | United States E&P
Disaggregation of Revenue [Line Items]
Assets	17,453	17,503
Revenues from contracts with customers	970	1,062
Operating Segments | International E&P
Disaggregation of Revenue [Line Items]
Assets	1,405	2,668
Revenues from contracts with customers	54	138
Not Allocated to Segments
Disaggregation of Revenue [Line Items]
Assets	857	1,239
Revenues from contracts with customers	$ 0	$ 0