Fair Value (Fair Value of the Fixed Income Securities Held in Nuclear Decommissioning Trust Funds) (Details) - Fixed income securities - Nuclear decommissioning trust fund $ in Millions	Mar. 31, 2026 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due within one year	$ 18
Due after one through five years	99
Due after five through ten years	139
Due after ten years	369
Fixed income securities total	$ 625