The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows as of December 31, 2020 and 2019:


	December 31, 2020						December 31, 2019
	Ameren		Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois
Cash and cash equivalents	$	139	$	136	$	—	$	16	$	9	$	—
Restricted cash included in “Other current assets”	17		5		6		14		4		5
Restricted cash included in “Other assets”	141		—		141		120		—		120
Restricted cash included in “Nuclear decommissioning trust fund”	4		4		—		26		26		—
Total cash, cash equivalents, and restricted cash	$	301	$	145	$	147	$	176	$	39	$	125

Restricted cash included in “Other current assets” primarily represents funds held by an irrevocable Voluntary Employee Beneficiary Association (VEBA) trust, which provides health care benefits for active employees. Restricted cash included in “Other assets” on Ameren’s and Ameren Illinois’ balance sheets primarily represents amounts collected under a cost recovery rider that are restricted for use in the procurement of renewable energy credits and amounts in a trust fund restricted for the use of funding certain asbestos-related claims.

“Accounts receivable – trade” on Ameren’s and Ameren Illinois’ balance sheets include certain receivables purchased at a discount from alternative retail electric suppliers that elect to participate in the utility consolidated billing program. At December 31, 2020 and 2019, “Other current liabilities” on Ameren’s and Ameren Illinois’ balance sheets included payables for purchased receivables of $28 million and $32 million, respectively.


	December 31, 2020						December 31, 2019
	Ameren Missouri		Ameren Illinois(a)		Ameren		Ameren Missouri		Ameren Illinois(a)		Ameren
Beginning of period	$	7	$	10	$	17	$	7	$	11	$	18
Bad debt expense	15		33		48		9		21		30

Net write-offs	(6)		(9)		(15)		(9)		(22)		(31)
End of period	$	16	$	34	$	50	$	7	$	10	$	17

(a)Ameren Illinois has riders that allow it to recover the difference between its actual net bad debt write-offs under GAAP, including those associated with receivables purchased from alternative retail electric suppliers, and the amount of net bad debt write-offs included in its base rates. In 2020, the rider for electric distribution allows for recovery of bad debt expense recognized under GAAP. See Note 2 – Rate and Regulatory Matters for additional information.

Net write-offs decreased for the year ended December 31, 2020 due to the temporary suspension of disconnecting customers for nonpayment. See Note 2 – Rate and Regulatory Matters for additional information.


	December 31, 2020						December 31, 2019
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren
Fuel(a)	$	115	$	—	$	115	$	126	$	—	$	126
Natural gas stored underground	5		52		57		6		57		63
Materials, supplies, and other	266		83		349		241		64		305
Total inventories	$	386	$	135	$	521	$	373	$	121	$	494


	December 31, 2020									December 31, 2019
	Ameren Missouri			Ameren Illinois			Ameren				Ameren Missouri			Ameren Illinois			Ameren
Beginning balance at January 1	$	687		$	4	(a)	$	691	(b)		$	646		$	4		$	650
Liabilities incurred	36		(c)	—			36		(c)		—			—			—
Liabilities settled	(58)			—			(58)				(20)			—			(20)
Accretion(d)	29			1			30				28			—			28
Change in estimates	57		(e)	—			57		(e)		33		(f)	—			33		(f)
Ending balance at December 31	$	751	(g)	$	5	(a)	$	756	(b), (g)		$	687		$	4	(a)	$	691	(b)

(d)Accretion expense attributable to Ameren Missouri and Ameren Illinois was recorded as a decrease to regulatory liabilities and an increase to regulatory assets, respectively.

(e)Ameren Missouri changed its fair value estimate primarily due to an update to the decommissioning of the Callaway Energy Center to reflect the cost study and funding analysis filed with the MoPSC in November 2020 and an increase in the cost estimate for closure of certain CCR storage facilities.

As of December 31, 2020, and 2019, “Other current liabilities” and “Other deferred credits and liabilities” on Ameren’s balance sheet included deferred compensation obligations of $90 million and $86 million, respectively, recorded at the present value of future benefits to be paid.

Ameren Missouri and Ameren Illinois collect from their customers excise taxes, including municipal and state excise taxes and gross receipts taxes, that are levied on the sale or distribution of natural gas and electricity. The following table presents the excise taxes recorded on a gross basis in “Operating Revenues – Electric,” “Operating Revenues – Natural gas” and “Operating Expenses – Taxes other than income taxes” on the statements of income for the years ended December 31, 2020, 2019, and 2018:

The following table presents the average rate that was applied to eligible construction work in progress and the amounts of allowance for funds used during construction capitalized in 2020, 2019, and 2018:


	2020			2019			2018
Average rate:
Ameren Missouri	5		%	6		%	7		%
Ameren Illinois	5		%	5		%	5		%
Ameren:
Allowance for equity funds used during construction	$	32		$	28		$	36
Allowance for borrowed funds used during construction	16			20			21
Total Ameren	$	48		$	48		$	57
Ameren Missouri:
Allowance for equity funds used during construction	$	19		$	19		$	27
Allowance for borrowed funds used during construction	10			12			14
Total Ameren Missouri	$	29		$	31		$	41
Ameren Illinois:
Allowance for equity funds used during construction	$	13		$	9		$	9
Allowance for borrowed funds used during construction	6			8			7
Total Ameren Illinois	$	19		$	17		$	16

Earnings per basic and diluted share are computed by dividing “Net Income Attributable to Ameren Common Shareholders” by the weighted-average number of basic and diluted common shares outstanding, respectively, during the applicable period. The weighted-average shares outstanding for earnings per diluted share includes the incremental effects resulting from performance share units, restricted stock units, and the forward sale agreement relating to common stock when the impact would be dilutive, as calculated using the treasury stock method. For information regarding performance share units and restricted stock units, see Note 11 – Stock-based Compensation. For information regarding the forward sale agreement, see Note 5 – Long-term Debt and Equity Financings.

The following table reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2020, 2019, and 2018:


	2020	2019	2018


Weighted-average Common Shares Outstanding – Basic	247.0	245.6	243.8
Assumed settlement of performance share units and restricted stock units	1.2	1.4	2.0
Dilutive effect of forward sale agreement	0.5	0.1	—
Weighted-average Common Shares Outstanding – Diluted(a)	248.7	247.1	245.8


	December 31, 2020						December 31, 2019							December 31, 2018
	Ameren		Ameren Missouri		Ameren Illinois			Ameren		Ameren Missouri		Ameren Illinois			Ameren		Ameren Missouri		Ameren Illinois
Investing


Accrued capital expenditures	$	400	$	183	$	218		$	333	$	140	$	163		$	272	$	121	$	138
Accrued nuclear fuel expenditures	—		—		—			19		19		—			20		20		—
Accrued wind generation expenditures	46		46		—			—		—		—			—		—		—
Net realized and unrealized gain (loss) – nuclear decommissioning trust fund	116		116		—			143		143		—			(38)		(38)		—
Exchange of bond investments for the extinguishment of senior unsecured notes(a)	—		—		—			17		—		17			—		—		—
Financing
Issuance of common stock for stock-based compensation	$	38	$	—	$	—		$	54	$	—	$	—		$	35	$	—	$	—
Exchange of bond investments for the extinguishment of senior unsecured notes(a)	—		—		—			(17)		—		(17)			—		—		—