Fair Value Measurement (Range and Arithmetic Average of Significant Unobservable Inputs) (Details) - Fair Value, Inputs, Level 3 [Member] - Fair Value Measurements Nonrecurring [Member] - Lower 48 [Member] $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) $ / MMBTU MMcf	Dec. 31, 2021 USD ($) MBoe $ / Boe	Dec. 31, 2020 USD ($) MBoe $ / Boe
Lower 48 Gulf Coast and Rockies noncore field [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure | $		$ 472
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Future prices annual increase (decrease), percentage		2.00%
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe		0.2
Price outlook | $ / Boe		41.45
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe		17
Price outlook | $ / Boe		93.68
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe		5.4
Price outlook | $ / Boe		64.39
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate		7.30%
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate		9.70%
Lower 48 Gulf Coast and Rockies noncore field [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate		8.70%
Wind River Basin [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure | $	$ 65
Wind River Basin [Member] | Measurement Input, Natural Gas [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Future prices annual increase (decrease), percentage	2.20%
Wind River Basin [Member] | Measurement Input, Natural Gas [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MMCFD | MMcf	8.4
Price outlook | $ / MMBTU	2.67
Wind River Basin [Member] | Measurement Input, Natural Gas [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MMCFD | MMcf	55.2
Price outlook | $ / MMBTU	9.17
Wind River Basin [Member] | Measurement Input, Natural Gas [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MMCFD | MMcf	22.9
Price outlook | $ / MMBTU	5.68
Wind River Basin [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate	7.90%
Wind River Basin [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate	9.10%
Wind River Basin [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate	8.30%
Central Basin Platform [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure | $			$ 244
Central Basin Platform [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Future prices annual increase (decrease), percentage			2.00%
Central Basin Platform [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe			0.5
Price outlook | $ / Boe			37.35
Central Basin Platform [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe			12.7
Price outlook | $ / Boe			115.29
Central Basin Platform [Member] | Measurement Input, Commodity Future Price [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Production MBOED | MBoe			3.4
Price outlook | $ / Boe			73.80
Central Basin Platform [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate			6.80%
Central Basin Platform [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate			7.70%
Central Basin Platform [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member] | Arithmetic Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount Rate			7.40%