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	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) $ / MMBTU $ / bbl bbl	Jun. 30, 2020 USD ($) $ / MMBTU $ / bbl Mcf bbl	Dec. 31, 2019 USD ($)
Sold Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		218
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.39	2.39
Fair value	$ 142	$ 142
Sold Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,107
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	72.54	72.54
Fair value	$ 36	$ 36
Sold Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		5,230
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	8.61	8.61
Fair value	$ 4	$ 4
Sold Fixed Price Swaps - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,748
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	23.01	23.01
Fair value	$ 10	$ 10
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		44
Fair value	1	$ 1
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		502
Fair value	9	$ 9
Two-way Costless-collars - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		184
Fair value	$ 1	$ 1
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.34	2.34
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	59.78	59.78
Two-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	29.40	29.40
Three-Way Costless Collars - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		59
Fair value	$ 0	$ 0
Three-Way Costless Collars - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		895
Fair value	$ 6	$ 6
Three-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.96	2.96
Three-way Costless-collars - 2020 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	57.55	57.55
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		321
Fair value	$ 143	$ 143
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,504
Fair value	51	$ 51
Financial protection on production - 2020 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,932
Fair value	$ 11	$ 11
Sold Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		36
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.53	2.53
Fair value	$ 1	$ 1
Sold Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		2,328
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	53.72	53.72
Fair value	$ 31	$ 31
Sold Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		5,889
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	7.12	7.12
Fair value	$ (3)	$ (3)
Sold Fixed Price Swaps - 2021 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		4,298
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	19.99	19.99
Fair value	$ 6	$ 6
Two-way Costless Collars-2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		55
Fair value	$ (5)	$ (5)
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	2.76	2.76
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		306
Fair value	$ (44)	$ (44)
Three-way Costless-collars - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,445
Fair value	$ 8	$ 8
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	2.85	2.85
Three-Way Costless Collars - 2021 Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	58.14	58.14
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		397
Fair value	$ (48)	$ (48)
Financial protection on production - 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		3,773
Fair value	$ 39	$ 39
Sold Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		438
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	51.74	51.74
Fair value	$ 4	$ 4
Sold Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Ethane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		136
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	7.35	7.35
Fair value	$ 0	$ 0
Sold Fixed Price Swaps - 2022 | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		105
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	19.43	19.43
Fair value	$ 0	$ 0
Two Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		29
Fair value	$ (1)	$ (1)
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	2.83	2.83
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		99
Fair value	$ (8)	$ (8)
Three-Way Costless Collars - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		666
Fair value	$ 3	$ 3
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	2.85	2.85
Three-way Costless Collars 2022 - Sold Calls | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	58.00	58.00
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		128
Fair value	$ (9)	$ (9)
Financial protection on production - 2022 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		1,104
Fair value	$ 7	$ 7
Three Way Costless Collars - 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		9
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	3.36	3.36
Sold Basis Swaps - 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		145
Basis differential per MMBtu | $ / MMBTU		(0.44)
Fair value	$ (11)	$ (11)
Sold Basis Swaps - 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		150
Basis differential per MMBtu | $ / MMBTU		(0.14)
Fair value	10	$ 10
Sold Basis Swaps - 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		122
Basis differential per MMBtu | $ / MMBTU		(0.46)
Fair value	(7)	$ (7)
Sold Basis Swaps | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		417
Fair value	$ (8)	$ (8)
Call Options 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		17
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.03	3.03
Fair value	$ (1)	$ (1)
Call Options 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		57
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.15	3.15
Fair value	$ (9)	$ (9)
Call Options 2021 | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		226
Cap price (in dollars per MMBtu, Bbl) | $ / bbl	60.00	60.00
Fair value	$ 0	$ 0
Call Options 2022 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		58
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.00	3.00
Fair value	$ (9)	$ (9)
Call Options 2023 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		17
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.84	2.84
Fair value	$ (3)	$ (3)
Call Options 2024 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		9
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	3.00	3.00
Fair value	$ (2)	$ (2)
Call Option | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		158
Fair value	$ (24)	$ (24)
Purchased Fixed Price Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		2
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.00	2.00
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ (1)	$ (1)
Purchased Basis Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.58)
Fair value	$ 0	$ 0
Sold Fixed Price Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		2
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	1.99	1.99
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 1	$ 1
Sold Basis Swaps, Storage, 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.51)
Fair value	$ 0	$ 0
Storage 2020 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		6
Fair value	$ 0	$ 0
Purchased Fixed Price Swaps, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.04	2.04
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 0	$ 0
Fixed Price Swap, Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		2
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.49	2.49
Basis differential per MMBtu | $ / MMBTU		0
Fair value	$ 0	$ 0
Sold Basis Swaps Storage, 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		1
Weighted average price (in dollars per MMBtu, Bbl) | $ / MMBTU	0	0
Basis differential per MMBtu | $ / MMBTU		(0.38)
Fair value	$ 0	$ 0
Storage 2021 | Not Designated as Hedging Instrument
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		4
Fair value	$ 0	$ 0
Purchased Fixed Price Swaps, Marketing, 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		5
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.35	2.35
Fair value	$ (2)	$ (2)
Purchased Fixed Price Swaps, Marketing, 2021 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		6
Cap price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.44	2.44
Fair value	$ 1	$ 1
Marketing 2020 | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Volume (Bcf, MBbls) | Mcf		11
Fair value	$ (1)	$ (1)
Fixed price swaps | Natural Gas
Derivative [Line Items]
Premium paid		$ 5	$ 9
Purchased fixed price swaps | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl		790
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	36.64	36.64
Fair value	$ 2	$ 2
Sold fixed price swaps | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Volume (Bcf, MBbls) | bbl	1,897
Weighted average price (in dollars per MMBtu, Bbl) | $ / bbl	57.60	57.60
Fair value	$ 34	$ 34
Short Puts | Three-way Costless-collars - 2020 Sold Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.18	2.18
Short Puts | Three-way Costless-collars - 2020 Sold Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	43.54	43.54
Short 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	2.16	2.16
Short 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	43.52	43.52
Short 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	2.08	2.08
Short 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	42.50	42.50
Short 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	2.16	2.16
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.12	2.12
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	56.83	56.83
Purchased Puts | Two-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Propane
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	25.20	25.20
Purchased Puts | Three-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Natural Gas
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / MMBTU	2.57	2.57
Purchased Puts | Three-way Costless-collars - 2020 Purchased Puts | Not Designated as Hedging Instrument | Oil
Derivative [Line Items]
Floor price (in dollars per MMBtu, Bbl) | $ / bbl	52.57	52.57
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	2.34	2.34
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	2.49	2.49
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	53.25	53.25
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	2.10	2.10
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	2.45	2.45
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	53.20	53.20
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	2.59	2.59