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Nuclear Decommissioning Trust Fund - Summary of Aggregate Fair Values and Realized Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Nuclear decommissioning trust fund
Fair Value	$ 879	$ 838
Unrealized Gains	376	346
Unrealized Losses	24	36
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	13	15
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	98	86
Unrealized Gains	1	0
Unrealized Losses	$ 4	$ 5
Weighted-average Maturities (In years)	11 years	11 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 101	$ 101
Unrealized Gains	0	0
Unrealized Losses	$ 8	$ 11
Weighted-average Maturities (In years)	26 years	26 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 34	$ 35
Unrealized Gains	0	0
Unrealized Losses	$ 3	$ 4
Weighted-average Maturities (In years)	29 years	30 years
Corporate debt securities
Nuclear decommissioning trust fund
Fair Value	$ 113	$ 114
Unrealized Gains	1	0
Unrealized Losses	$ 9	$ 13
Weighted-average Maturities (In years)	11 years	12 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 519	$ 486
Unrealized Gains	374	346
Unrealized Losses	0	3
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	1	1
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	20 years	17 years

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The weighted-average maturity period for securities of nuclear decommissioning trust funds assets.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
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The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

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