Short-Term Debt And Liquidity (Narrative) (Details) $ in Billions	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021	Jun. 30, 2022 USD ($)	Jun. 30, 2021
Credit Agreements
Short-term Debt [Line Items]
Net Liquidity Available	$ 1.3		$ 1.3
Actual debt-to-capital ratio	0.59		0.59
Utilities
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate, over Time	0.98%	0.22%	0.69%	0.22%
Union Electric Company | Missouri Credit Agreement
Short-term Debt [Line Items]
Actual debt-to-capital ratio	0.51		0.51
Ameren Illinois Company | Illinois Credit Agreement
Short-term Debt [Line Items]
Actual debt-to-capital ratio	0.44		0.44