Schedule I - Condensed Financial Information Of Parent Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	$ 304	$ 295	$ 184
Donations	(5)	(24)	(26)
Total other income (expense), net	417	348	226
Ameren (parent)
Other Nonoperating Income (Expense) [Line Items]
Non-state-regulated money pool advances	14	10
Non-service cost components of net periodic benefit income	4	8	3
Donations	0	(18)	(15)
Other expense, net	(1)	(1)	(1)
Total other income (expense), net	$ 3	$ (11)	$ (13)