Fair Value Measurements - NPC (Details) - Recurring - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Assets:
Assets, fair value	$ 6,042	$ 3,566
Investment funds
Assets:
Equity securities	243	283
Money market mutual funds
Assets:
Money market mutual funds	3,986	1,469
Level 1
Assets:
Assets, fair value	5,103	2,648
Level 1 \| Investment funds
Assets:
Equity securities	243	283
Level 1 \| Money market mutual funds
Assets:
Money market mutual funds	3,986	1,469
Level 2
Assets:
Assets, fair value	931	916
Level 2 \| Investment funds
Assets:
Equity securities	0	0
Level 2 \| Money market mutual funds
Assets:
Money market mutual funds	0	0
Level 3
Assets:
Assets, fair value	12	10
Level 3 \| Investment funds
Assets:
Equity securities	0	0
Level 3 \| Money market mutual funds
Assets:
Money market mutual funds	0	0
Commodity derivatives \| Level 1
Liabilities:
Commodity derivatives	(15)	(13)
Commodity derivatives \| Level 2
Liabilities:
Commodity derivatives	(136)	(169)
Commodity derivatives \| Level 3
Liabilities:
Commodity derivatives	(67)	(56)
NPC
Assets:
Assets, fair value	83	24
NPC \| Investment funds
Assets:
Equity securities	6	5
NPC \| Money market mutual funds
Assets:
Money market mutual funds	77	19
NPC \| Level 1
Assets:
Assets, fair value	83	24
NPC \| Level 1 \| Investment funds
Assets:
Equity securities	6	5
NPC \| Level 1 \| Money market mutual funds
Assets:
Money market mutual funds	77	19
NPC \| Level 2
Assets:
Assets, fair value	0	0
NPC \| Level 2 \| Investment funds
Assets:
Equity securities	0	0
NPC \| Level 2 \| Money market mutual funds
Assets:
Money market mutual funds	0	0
NPC \| Level 3
Assets:
Assets, fair value	0	0
NPC \| Level 3 \| Investment funds
Assets:
Equity securities	0	0
NPC \| Level 3 \| Money market mutual funds
Assets:
Money market mutual funds	0	0
NPC \| Commodity derivatives
Liabilities:
Commodity derivatives	(51)	(41)
NPC \| Commodity derivatives \| Level 1
Liabilities:
Commodity derivatives	0	0
NPC \| Commodity derivatives \| Level 2
Liabilities:
Commodity derivatives	0	0
NPC \| Commodity derivatives \| Level 3
Liabilities:
Commodity derivatives	$ (51)	$ (41)

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 182
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480401/815-10-55-182

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-7A

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-22

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-15

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5C
-Subparagraph (SX 210.12-13C(Column F))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5C

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5B
-Subparagraph (SX 210.12-13B(Column E))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5B

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