Short-Term Debt And Liquidity (Tables)

12 Months Ended

Dec. 31, 2017

Short-term Debt [Line Items]

Schedule Of Maximum Aggregate Amount Available On Credit Agreements

The following table presents the maximum aggregate amount available to each borrower under each facility:

	Missouri Credit Agreement		Illinois Credit Agreement
Ameren (parent)	$	700	$	500
Ameren Missouri	800		(a)
Ameren Illinois	(a)		800

(a) Not applicable.

Schedule of Commercial Paper

The following table summarizes the borrowing activity and relevant interest rates under Ameren (parent)’s, Ameren Missouri’s and Ameren Illinois’ commercial paper programs for the years ended December 31, 2017 and 2016:

	Ameren (parent)			Ameren Missouri			Ameren Illinois			Ameren Consolidated
2017
Average daily commercial paper outstanding	$	573		$	5		$	90		$	668
Outstanding borrowings at period-end	383			39			62			484
Weighted-average interest rate	1.30		%	1.24		%	1.35		%	1.31		%
Peak outstanding commercial paper during period(a)	$	841		$	64		$	469		$	948
Peak interest rate	1.90		%	1.78		%	2.00		%	2.00		%
2016
Average daily commercial paper outstanding	$	440		$	60		$	52		$	552
Outstanding borrowings at period-end	507			—			51			558
Weighted-average interest rate	0.82		%	0.74		%	0.69		%	0.80		%
Peak outstanding commercial paper during period(a)	$	574		$	208		$	195		$	839
Peak interest rate	1.05		%	0.85		%	0.90		%	1.05		%

(a) The timing of peak outstanding commercial paper issuances varies by company. Therefore, the sum of the peak amounts presented by the companies may not equal the Ameren consolidated peak amount for the period.