Revenues Revenues from Contracts with Customers by Product Type and Geographic Areas (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 5,063	$ 5,902	$ 4,247
United States E&P
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,602	4,886
United States E&P | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,600	1,912
United States E&P | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,771	1,668
United States E&P | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	697	791
United States E&P | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	358	293
United States E&P | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	176	222
United States E&P | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,887	3,947
United States E&P | Crude oil and condensate | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,358	1,554
United States E&P | Crude oil and condensate | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,686	1,568
United States E&P | Crude oil and condensate | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	425	426
United States E&P | Crude oil and condensate | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	316	235
United States E&P | Crude oil and condensate | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	102	164
United States E&P | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	307	495
United States E&P | Natural gas liquids | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	114	205
United States E&P | Natural gas liquids | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	46	62
United States E&P | Natural gas liquids | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	116	181
United States E&P | Natural gas liquids | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	26	38
United States E&P | Natural gas liquids | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5	9
United States E&P | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	349	413
United States E&P | Natural gas | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	121	145
United States E&P | Natural gas | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	39	38
United States E&P | Natural gas | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	156	184
United States E&P | Natural gas | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	16	20
United States E&P | Natural gas | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	17	26
United States E&P | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	59	31
United States E&P | Other | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7	8
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	52	23
International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	461	1,016
International | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	307	384
International | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	134	359
International | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		196
International | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	20	77
International | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	398	888
International | Crude oil and condensate | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	271	342
International | Crude oil and condensate | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	107	282
International | Crude oil and condensate | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		187
International | Crude oil and condensate | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	20	77
International | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5	9
International | Natural gas liquids | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4	4
International | Natural gas liquids | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	5
International | Natural gas liquids | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
International | Natural gas liquids | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
International | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	44	86
International | Natural gas | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	32	37
International | Natural gas | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	12	40
International | Natural gas | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		9
International | Natural gas | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
International | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	14	33
International | Other | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	1
International | Other | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	14	32
International | Other | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
International | Other | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 0	$ 0