Property and Plant, Net (Schedule of Capitalized Software and Deferred Cloud Implementation Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	$ 224	$ 212	$ 159
Capitalized Computer Software, Gross	1,996	1,823
Capitalized Computer Software, Accumulated Amortization	(1,348)	(1,126)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	20	17	15
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	157	142
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(71)	(51)
Ameren Missouri | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	118	114	85
Capitalized Computer Software, Gross	881	795
Capitalized Computer Software, Accumulated Amortization	(567)	(453)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	9	8	7
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	71	63
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	(32)	(23)
Ameren Illinois | Capitalized software costs
Finite-Lived Intangible Assets [Line Items]
Capitalized Computer Software, Amortization	100	92	69
Capitalized Computer Software, Gross	867	786
Capitalized Computer Software, Accumulated Amortization	(552)	(452)
Hosting Arrangement, Service Contract, Implementation Cost, Expense, Amortization	10	9	$ 8
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, before Accumulated Amortization	82	76
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization	$ (36)	$ (26)
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