Amount of megawatts

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Frequency of Integrated Resource Plan Filings

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- Definition

Large load customer rate plan megawatts requested

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Minimum demand charges as percentage of contracted capacity for large load customer rate plan

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Minimum service term for large load customer rate plan

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Number of days after end of test year to perform reconciliation when using a future test year

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- Definition

Deferral percentage of the depreciation expense on certain property, plant, and equipment placed in-service and not included in base rates.

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- Definition

Rate And Regulatory Matters [Line Items]

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
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Amount of public utility's approved rate increase (decrease) by regulatory agency.

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Percentage of public utility's approved rate increase (decrease) by regulatory agency.

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Amount of operating expense for depreciation and amortization of regulated operation.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(2)(b))
-Publisher FASB
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Rate And Regulatory Matters (Narrative-Missouri) (Details) $ in Millions	3 Months Ended								6 Months Ended
	Sep. 30, 2027	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($) MWh	Jun. 30, 2024 USD ($) MWh	Jun. 30, 2023 MWh	Mar. 31, 2023 MWh	Jun. 30, 2025 USD ($) MWh	Jun. 30, 2024 USD ($)
Rate And Regulatory Matters [Line Items]
Depreciation and amortization					$ 386	$ 376			$ 753	$ 737
Capital expenditures									$ 2,130	1,892
Union Electric Company
Rate And Regulatory Matters [Line Items]
PISA Deferral Percentage									85.00%
Depreciation and amortization					209	$ 208			$ 403	403
Capital expenditures									$ 1,325	$ 1,104
Union Electric Company \| Maximum
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage									2.50%
Union Electric Company \| Maximum \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage			2.25%
Union Electric Company \| Natural Gas Generation Facility
Rate And Regulatory Matters [Line Items]
Capital expenditures									$ 900
Union Electric Company \| Solar Generation Facilities
Rate And Regulatory Matters [Line Items]
Capital expenditures									$ 800
Union Electric Company \| Electric
Rate And Regulatory Matters [Line Items]
Large load customer rate plan megawatts requested \| MWh									100
Minimum service term for large load customer rate plan									15 years
Minimum demand charges as percentage of contracted capacity for large load customer rate plan									70.00%
Union Electric Company \| Electric \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Frequency of Integrated Resource Plan Filings	4 years
Union Electric Company \| Electric \| Final Rate Order
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount					$ 355
Union Electric Company \| Electric \| Final Rate Order \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Depreciation and amortization				$ 70
Union Electric Company \| Natural gas \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Number of days after end of test year to perform reconciliation when using a future test year		45 days
Union Electric Company \| Natural gas \| Final Rate Order \| Subsequent Event
Rate And Regulatory Matters [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount				$ 32
Union Electric Company \| Self-build \| Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh							50	50
Union Electric Company \| Self-build \| Natural Gas Generation Facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh					800	800
Union Electric Company \| Self-build \| Energy Storage Facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh					400
Union Electric Company \| Build-transfer \| Solar generation facility
Rate And Regulatory Matters [Line Items]
Amount of Megawatts \| MWh							300