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Callaway Energy Center (Cost and Fair Values of Investments In Debt Securities in Nuclear Decommissioning Trust Fund According to Contractual Maturities) (Details) $ in Millions	Dec. 31, 2025 USD ($)
Nuclear Waste Matters [Abstract]
Cost, Less than 5 years	$ 207
Cost, 5 years to 10 years	139
Cost, Due after 10 years	142
Cost, Total	488
Fair Value, Less than 5 years	208
Fair Value, 5 years to 10 years	141
Fair Value, Due after 10 years	137
Fair Value, Total	$ 486

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Nuclear Waste Matters [Abstract]

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