Property and Plant, Net (Schedule of Capitalized Software and Deferred Cloud Implementation Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	$ 212	$ 159	$ 125
Capitalized Computer Software, Gross	1,823	1,443
Capitalized Computer Software, Accumulated Amortization	(1,126)	(914)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	17	15	13
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	142	106
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(51)	(34)
Ameren Missouri | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	114	85	66
Capitalized Computer Software, Gross	795	613
Capitalized Computer Software, Accumulated Amortization	(453)	(339)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	8	7	6
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	63	48
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(23)	(15)
Ameren Illinois | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	92	69	53
Capitalized Computer Software, Gross	786	601
Capitalized Computer Software, Accumulated Amortization	(452)	(360)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	9	8	$ 6
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	76	54
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	$ (26)	$ (17)
Minimum | Software and Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum | Software and Software Development Costs
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Maximum | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years