Fair Value Measurement - Impairment (Details) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Property, plant, and equipment impairment		$ 587		$ 587
Goodwill, Impairment Loss		159
Asset Impairment	$ 0		$ 0	746	$ 0
Equity Method Investment, Other than Temporary Impairment		61		$ 61
Total Impairment Charges, including Equity Method Investments		807
Level 3
Impaired Long-Lived Assets Held and Used [Line Items]
Property, Plant, and Equipment		96
Goodwill		0
Assets		352
Equity Method Investments, Fair Value Disclosure		$ 256
Level 3 | Valuation Technique, Discounted Cash Flow | Measurement Input, Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		14
Level 3 | Valuation Technique, Discounted Cash Flow | Measurement Input, Terminal Value Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		8
Level 3 | Arithmetic Average | Market Approach Valuation Technique | Measurement Input, EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Goodwill, Measurement Input		8
Level 3 | Arithmetic Average | Oil | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		55.98
Level 3 | Arithmetic Average | Natural Gas [Member] | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		3.35
Level 3 | Arithmetic Average | Natural Gas Liquids | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		0.52
Level 3 | Minimum | Market Approach Valuation Technique | Measurement Input, EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Goodwill, Measurement Input		5.2
Level 3 | Minimum | Oil | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		34.52
Level 3 | Minimum | Natural Gas [Member] | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		2.28
Level 3 | Minimum | Natural Gas Liquids | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		0.30
Level 3 | Maximum | Market Approach Valuation Technique | Measurement Input, EBITDA Multiple
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Goodwill, Measurement Input		16.5
Level 3 | Maximum | Oil | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		67.61
Level 3 | Maximum | Natural Gas [Member] | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		4.12
Level 3 | Maximum | Natural Gas Liquids | Valuation Technique, Discounted Cash Flow | Measurement Input, Commodity Future Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Measurement Input		0.62