Supplemental Information (Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplemental Cash Flow Information [Line Items]
Wind generation expenditures		$ 525	$ 564
Accrued capital expenditures	$ 441	524	446
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund	(218)	163	116
Stock Issued		33
Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued	31	33	38
Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued	8	0	0
Union Electric Company
Supplemental Cash Flow Information [Line Items]
Wind generation expenditures		525	564
Accrued capital expenditures	243	301	229
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund	(218)	163	116
Union Electric Company | Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued	0	0	0
Union Electric Company | Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued	0	0	0
Ameren Illinois Company
Supplemental Cash Flow Information [Line Items]
Accrued capital expenditures	181	215	218
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund	0	0	0
Ameren Illinois Company | Issuance of common stock for stock-based compensation
Supplemental Cash Flow Information [Line Items]
Stock Issued	0	0	0
Ameren Illinois Company | Issuance of common stock under the DRPlus
Supplemental Cash Flow Information [Line Items]
Stock Issued	$ 0	$ 0	$ 0