Derivatives and Risk Management (Schedule of Derivative Instruments Notional Amount, Weighted Average Contract Prices and Fair Value) (Details) bbl in Thousands, Mcf in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) $ / bbl $ / MMBTU Mcf bbl
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	589.0
Fair value	$ (8)
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	4,926
Fair value	$ (41)
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	4,869
Fair value	$ (11)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	176.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.79
Fair value	$ 14
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	3,272
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	49.27
Fair value	$ (29)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	4,429
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	7.17
Fair value	$ (11)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	5,443
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	20.84
Fair value	$ (69)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Normal Butane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,568
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	25.30
Fair value	$ (19)
Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gasoline
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,513
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	37.91
Fair value	$ (27)
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	195.0
Fair value	$ 1
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	156
Fair value	$ (2)
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	440
Fair value	$ 0
Two-way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.93
Two-way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	45.73
Two-way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	10.40
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	218.0
Fair value	$ (23)
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,498
Fair value	$ (10)
Three-Way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.84
Three-Way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	53.10
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	453.0
Fair value	$ (18)
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	3,099
Fair value	$ (14)
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,893
Fair value	$ (1)
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	3,028
Fair value	$ (15)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	112.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.68
Fair value	$ (2)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,719
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	48.54
Fair value	$ (10)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,758
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	8.68
Fair value	$ (1)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	2,723
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	21.83
Fair value	$ (14)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Normal Butane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	888
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	24.47
Fair value	$ (5)
Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gasoline
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	857
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	40.48
Fair value	$ (8)
Two Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	63.0
Fair value	$ (3)
Two Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	135
Fair value	$ 0
Two Way Costless Collars - 2022 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.03
Two Way Costless Collars - 2022 Sold Calls | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	9.66
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	278.0
Fair value	$ (13)
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,380
Fair value	$ (4)
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	305
Fair value	$ (1)
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.97
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	57.05
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	31.92
Three Way Costless Collars - 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	103.0
Fair value	$ (4)
Three Way Costless Collars - 2023 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,268
Fair value	$ (4)
Three Way Costless Collars - 2023 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.01
Three Way Costless Collars - 2023 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	56.12
Basis Swaps | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	605.0
Fair value	$ 68
Basis Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	233.0
Basis differential per MMBtu | $ / MMBTU	(0.49)
Fair value	$ 39
Basis Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	220.0
Basis differential per MMBtu | $ / MMBTU	(0.44)
Fair value	$ 24
Basis Swap - 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	119.0
Basis differential per MMBtu | $ / MMBTU	(0.56)
Fair value	$ 4
Basis Swap - 2024 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	24.0
Basis differential per MMBtu | $ / MMBTU	(0.64)
Fair value	$ 1
Basis Swap - 2025 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	9.0
Basis differential per MMBtu | $ / MMBTU	(0.64)
Fair value	$ 0
Call options | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	189.0
Fair value	$ (33)
Call Options 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	57.0
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.19
Fair value	$ (4)
Call Options 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	171
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	60.00
Fair value	$ (1)
Call Options 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	77.0
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.00
Fair value	$ (16)
Call Options 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	46.0
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.94
Fair value	$ (10)
Call Options 2024 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	9.0
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.00
Fair value	$ (3)
Put options | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	19.0
Fair value	$ (1)
Put Option 2021 | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	14.0
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.00
Fair value	$ 0
Put Option 2022 | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	5.0
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.00
Fair value	$ (1)
Swaption 2021 | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	18.0
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.00
Fair value	$ (1)
Storage 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	3.0
Fair value	$ 0
Purchased Fixed Price Swaps, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	2.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.34
Basis differential per MMBtu | $ / MMBTU	0
Fair value	$ 0
Purchased Basis Swaps Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	1.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0
Basis differential per MMBtu | $ / MMBTU	(0.88)
Fair value	$ 0
Fixed Price Swap, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	0.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.23
Basis differential per MMBtu | $ / MMBTU	0
Fair value	$ 0
Basis Swaps Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	0.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0
Basis differential per MMBtu | $ / MMBTU	(0.57)
Fair value	$ 0
Storage 2022 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	3.0
Fair value	$ 0
Purchased Fixed Price Swaps, Storage, 2022 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	0.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.14
Basis differential per MMBtu | $ / MMBTU	0
Fair value	$ 0
Fixed Price Swap, Storage, 2022 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	2.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.82
Basis differential per MMBtu | $ / MMBTU	0
Fair value	$ 0
Basis Swaps Storage, 2022 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	1.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0
Basis differential per MMBtu | $ / MMBTU	(0.57)
Fair value	$ 0
Purchased Fixed Price Swaps, Marketing, 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf	4.0
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.44
Fair value	$ 1
Sold Puts | Three-Way Costless Collars - 2021 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.17
Sold Puts | Three-Way Costless Collars - 2021 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	37.86
Sold Puts | Three-Way Costless Collars - 2022 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.06
Sold Puts | Three-Way Costless Collars - 2022 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	39.89
Sold Puts | Three-Way Costless Collars - 2022 Sold Puts | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	16.80
Sold Puts | Three Way Costless Collars - 2023 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.05
Sold Puts | Three Way Costless Collars - 2023 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	33.97
Purchased Puts | Two-way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.57
Purchased Puts | Two-way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	37.79
Purchased Puts | Two-way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	7.14
Purchased Puts | Three-Way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.50
Purchased Puts | Three-Way Costless Collars - 2021 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	47.70
Purchased Puts | Two Way Costless Collars - 2022 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.52
Purchased Puts | Two Way Costless Collars - 2022 Purchased Puts | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	7.56
Purchased Puts | Three Way Costless Collars 2022 - Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.50
Purchased Puts | Three Way Costless Collars 2022 - Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	50.23
Purchased Puts | Three Way Costless Collars 2022 - Purchased Puts | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	21.00
Purchased Puts | Three Way Costless Collars - 2023 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.46
Purchased Puts | Three Way Costless Collars - 2023 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	45.51