Revenue Recognition - Disaggregated Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 4,517	$ 5,189
Gains (losses) on oil, natural gas and NGL derivatives	5	(34)
Total oil, natural gas and NGL revenues	8,595	10,030	$ 10,039
Marcellus
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	856	924
Haynesville
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	620	838
Eagle Ford
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,561	1,872
Brazos valley
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	769
Powder River Basin
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	478	350
Mid-Continent
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	233	385
Utica
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		820
Oil
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,543	2,201
Gains (losses) on oil, natural gas and NGL derivatives	(212)	124
Oil | Marcellus
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Oil | Haynesville
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	2
Oil | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,289	1,514
Oil | Brazos valley
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	721
Oil | Powder River Basin
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	369	244
Oil | Mid-Continent
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164	246
Oil | Utica
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		195
Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,782	2,486
Gains (losses) on oil, natural gas and NGL derivatives	217	(147)
Natural gas | Marcellus
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	856	924
Natural gas | Haynesville
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	620	836
Natural gas | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	153	173
Natural gas | Brazos valley
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	32
Natural gas | Powder River Basin
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	77	68
Natural gas | Mid-Continent
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	44	84
Natural gas | Utica
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		401
NGL
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	192	502
Gains (losses) on oil, natural gas and NGL derivatives	0	(11)
NGL | Marcellus
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
NGL | Haynesville
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
NGL | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	119	185
NGL | Brazos valley
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	16
NGL | Powder River Basin
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	32	38
NGL | Mid-Continent
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	25	55
NGL | Utica
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		224
Oil, Natural Gas and NGL
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	4,522	5,155	$ 4,985
Oil, Natural Gas and NGL | Oil
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	2,331	2,325
Oil, Natural Gas and NGL | Natural gas
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	1,999	2,339
Oil, Natural Gas and NGL | NGL
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	192	491
Marketing
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,619	4,390
Gains (losses) on oil, natural gas and NGL derivatives	(4)	7
Total oil, natural gas and NGL revenues	3,967	5,076
Marketing | Oil
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,473	2,740
Gains (losses) on oil, natural gas and NGL derivatives	0	0
Total oil, natural gas and NGL revenues	2,784	3,197
Marketing | Natural gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	900	1,194
Gains (losses) on oil, natural gas and NGL derivatives	(4)	7
Total oil, natural gas and NGL revenues	937	1,423
Marketing | NGL
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	246	456
Gains (losses) on oil, natural gas and NGL derivatives	0	0
Total oil, natural gas and NGL revenues	246	456
Other marketing revenue
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	352	679
Other marketing revenue | Oil
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	311	457
Other marketing revenue | Natural gas
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	41	222
Other marketing revenue | NGL
Disaggregation of Revenue [Line Items]
Total oil, natural gas and NGL revenues	$ 0	$ 0