Regulatory Matters - NPC - Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Total regulatory assets	$ 5,062	$ 3,963
Regulatory assets, current	1,319	544
Regulatory assets, noncurrent	3,743	3,419
Regulatory assets not earning a return on investment	$ 2,300	1,800
Unrealized losses on regulated derivative contracts
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 112	157
Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory asset, amortization period	15 years
Total regulatory assets	$ 835	742
Deferred operating costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	10 years
Total regulatory assets	$ 83	103
NPC
Regulatory Assets [Line Items]
Total regulatory assets	1,294	1,019
Regulatory assets, current	666	291
Regulatory assets, noncurrent	628	728
Regulatory assets not earning a return on investment	$ 320	371
NPC | Deferred energy costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 654	273
NPC | Decommissioning costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	3 years
Total regulatory assets	$ 116	169
NPC | Merger costs from 1999 merger
Regulatory Assets [Line Items]
Regulatory asset, amortization period	22 years
Total regulatory assets	$ 105	110
NPC | Unrealized losses on regulated derivative contracts
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 75	117
NPC | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory asset, amortization period	5 years
Total regulatory assets	$ 69	73
NPC | Deferred operating costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	13 years
Total regulatory assets	$ 67	93
NPC | Other
Regulatory Assets [Line Items]
Total regulatory assets	$ 208	$ 184