Schedule I - Condensed Financial Information Of Parent Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	$ 295	$ 184	$ 136
Donations	(24)	(26)	(9)
Total other expense, net	348	226	202
Ameren (parent)
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	8	3	1
Donations	(18)	(15)	0
Other expense, net	(1)	(1)	(1)
Total other expense, net	(11)	$ (13)	$ 0
Non-state-regulated money pool advances	$ 10