Property and Plant, Net (Schedule of Capitalized Software) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Amortization Expense	$ 159	$ 125	$ 93
Gross Carrying Value	1,443	1,199
Accumulated Amortization	(914)	(757)
Union Electric Company \| Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Amortization Expense	85	66	44
Gross Carrying Value	613	523
Accumulated Amortization	(339)	(255)
Ameren Illinois Company \| Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Amortization Expense	69	53	$ 45
Gross Carrying Value	601	452
Accumulated Amortization	$ (360)	$ (291)
Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years

For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs.

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Amount of expense for amortization of capitalized computer software costs.

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Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

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