Hedging Activities and Fair Value Measurements, Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Financial assets [Abstract]
Interest rate derivatives	$ 2
Value before application of CME Rule 814	1,032	$ 798
Impact of CME Rule 814	(355)	(223)
Total commodity derivatives	677	575
Total	679	575
Commodity derivatives:
Value before application of CME Rule 814	967	716
Impact of CME Rule 814	(416)	(221)
Total commodity derivatives	551	495
Total	551	495
Net value before application of CME Rule 814 to commodity hedging portfolio	65
Level 1 [Member]
Financial assets [Abstract]
Interest rate derivatives	0
Value before application of CME Rule 814	292	355
Impact of CME Rule 814	(57)	(56)
Total commodity derivatives	235	299
Total	235	299
Commodity derivatives:
Value before application of CME Rule 814	330	291
Impact of CME Rule 814	(125)	(43)
Total commodity derivatives	205	248
Total	205	248
Level 2 [Member]
Financial assets [Abstract]
Interest rate derivatives	2
Value before application of CME Rule 814	740	443
Impact of CME Rule 814	(298)	(167)
Total commodity derivatives	442	276
Total	444	276
Commodity derivatives:
Value before application of CME Rule 814	637	404
Impact of CME Rule 814	(291)	(157)
Total commodity derivatives	346	247
Total	346	247
Level 3 [Member]
Financial assets [Abstract]
Interest rate derivatives	0
Value before application of CME Rule 814	0	0
Impact of CME Rule 814	0	0
Total commodity derivatives	0	0
Total	0	0
Commodity derivatives:
Value before application of CME Rule 814	0	21
Impact of CME Rule 814	0	(21)
Total commodity derivatives	0	0
Total	$ 0	$ 0