Rate And Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2021

Public Utilities, General Disclosures [Abstract]

Schedule of Regulatory Frameworks and Significant Recovery Mechanisms

The following table presents the regulatory frameworks and significant regulatory recovery mechanisms for each of Ameren’s rate-regulated businesses, which are discussed in more detail below:

	Ameren Missouri	Ameren Illinois’ electric distribution business	Ameren Illinois’ natural gas delivery service business	Ameren Illinois’ and ATXI’s electric transmission business
Regulatory framework	•Historical test year ratemaking •Natural gas revenues for residential customers adjusted for sales volume deviations resulting from weather through the WNAR	•Performance-based formula ratemaking •Initial rates based on historical test year and expected net plant additions for the year before rates become effective •Revenues decoupled from sales volumes	•Future test year ratemaking •Revenues for residential and small nonresidential customers decoupled from sales volumes through the VBA	•Formula ratemaking •Initial rates based on future test year •Revenues decoupled from sales volumes
Regulatory mechanisms	•PISA Riders: •RESRAM •FAC •MEEIA •PGA •WNAR Trackers: •Pension and postretirement benefit costs •Certain excess deferred income taxes •Renewable energy standard costs	•Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments Riders: •Power procurement •Transmission services •Renewable energy credit compliance •Zero emission credits •Certain environmental costs •Bad debt write-offs •Costs of certain asbestos-related claims	Riders: •QIP •PGA •VBA •Energy-efficiency program costs •Certain environmental costs •Bad debt write-offs •Invested capital taxes	•Revenue requirement reconciliation adjustment

Schedule Of Regulatory Assets And Liabilities

The following table presents our regulatory assets and regulatory liabilities at December 31, 2021 and 2020:

	2021						2020
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren
Regulatory assets:
Under-recovered FAC(a)	$	47	$	—	$	47	$	48	$	—	$	48
Under-recovered PGA(b)(c)	49		114		163		—		2		2
MTM derivative losses(d)	77		125		202		21		200		221
IEIMA revenue requirement reconciliation adjustment(e)(f)	—		42		42		—		—		—
FERC revenue requirement reconciliation adjustment(g)	—		18		43		—		28		50
Under-recovered VBA(h)	—		17		17		—		11		11
Income taxes(i)	115		69		185		117		65		183
Bad debt rider(j)	—		8		8		—		11		11
Callaway refueling and maintenance outage costs(k)	14		—		14		39		—		39
Unamortized loss on reacquired debt(l)	50		13		63		52		22		74
Environmental cost riders(m)	—		70		70		—		93		93
Storm costs(f)(n)	—		17		17		—		7		7
Allowance for funds used during construction for pollution control equipment(f)(o)	13		—		13		15		—		15
Customer generation rebate program(f)(p)	—		47		47		—		17		17
PISA(f)(q)	244		—		244		78		—		78
FEJA energy-efficiency rider(f)(r)	—		350		350		—		283		283
Other	41		42		83		37		40		77
Total regulatory assets	$	650	$	932	$	1,608	$	407	$	779	$	1,209
Less: current regulatory assets	(127)		(180)		(319)		(60)		(37)		(109)
Noncurrent regulatory assets	$	523	$	752	$	1,289	$	347	$	742	$	1,100
Regulatory liabilities:
Over-recovered FAC(a)	$	19	$	—	$	19	$	10	$	—	$	10
Over-recovered Illinois electric power costs(b)	—		13		13		—		15		15
Over-recovered PGA(b)	—		1		1		7		15		22
MTM derivative gains(d)	50		41		91		11		10		21
IEIMA revenue requirement reconciliation adjustment(e)	—		—		—		—		22		22
FERC revenue requirement reconciliation adjustment(g)	—		2		4		—		21		21
Income taxes(i)	1,208		770		2,066		1,317		790		2,192
Cost of removal(s)	1,028		929		1,988		1,027		873		1,923
AROs(t)	603		—		603		436		—		436
Bad debt rider(j)	—		19		19		—		5		5
Pension and postretirement benefit costs(u)	399		392		791		198		177		375
Pension and postretirement benefit costs tracker(v)	28		—		28		55		—		55
Renewable energy credits and zero emission credits(w)	—		246		246		—		200		200
RESRAM(x)	19		—		19		2		—		2
Excess income taxes collected in 2018(y)	25		—		25		45		—		45
Other	32		15		48		28		23		59
Total regulatory liabilities	$	3,411	$	2,428	$	5,961	$	3,136	$	2,151	$	5,403
Less: current regulatory liabilities	(57)		(54)		(113)		(26)		(88)		$	(121)
Noncurrent regulatory liabilities	$	3,354	$	2,374	$	5,848	$	3,110	$	2,063	$	5,282

(a)Under-recovered or over-recovered fuel costs to be recovered or refunded through the FAC. Specific accumulation periods aggregate the under-recovered or over-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from, or refund to, customers that occurs over the next eight months.

(b)Under-recovered or over-recovered costs from utility customers. Amounts will be recovered from, or refunded to, customers within one year of the deferral.

(c)As a result of the significant increase in customer demand and prices for natural gas and electricity experienced in mid-February 2021 due to extremely cold weather, for the month of February 2021, Ameren Missouri and Ameren Illinois had under-recovered costs under their PGA clauses of $53 million and $221 million, respectively. Pursuant to an October 2021 MoPSC order, the collection period for Ameren Missouri’s cumulative PGA under-recovery as of August 2021, which includes the February 2021 under-recovery, was extended from 12 months to 36 months, beginning November 2021. Ameren Illinois is collecting its February 2021 PGA under-recovery over 18 months beginning April 2021, but the collection of the remaining balance may be extended at Ameren Illinois’ election to lessen the impact on customer rates.

(d)Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.

(e)The difference between Ameren Illinois’ electric distribution service annual revenue requirement calculated under the performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. Any under-recovery or over-recovery will be recovered from, or refunded to, customers with interest within two years.

(f)These assets earn a return at the applicable WACC.

(g)Ameren Illinois’ and ATXI’s annual revenue requirement reconciliation calculated pursuant to the FERC’s electric transmission formula ratemaking framework. Any under-recovery or over-recovery will be recovered from, or refunded to, customers within two years.

(h)Under-recovered natural gas revenue caused by sales volume deviations from weather normalized sales approved by the ICC in rate regulatory reviews. Each year’s amount will be recovered from customers from April through December of the following year.

(i)The regulatory assets represent amounts that will be recovered from customers for deferred income taxes related to the equity component of allowance for funds used during construction and the effects of tax rate increases. The regulatory liabilities represent amounts that will be refunded to customers for deferred income taxes related to depreciation differences, other tax liabilities, and the unamortized portion of investment tax credits recorded at rates in excess of current statutory rates. Amounts associated with the equity component of allowance for funds used during construction and the unamortized portion of investment tax credits will be amortized over the expected life of the related assets. For net regulatory liabilities related to deferred income taxes recorded at rates other than the current statutory rate, the weighted-average remaining amortization periods at Ameren, Ameren Missouri, and Ameren Illinois are 35, 28, and 42 years.

(j)A rider for the difference between the level of bad debt write-offs, net of any subsequent recoveries, incurred by Ameren Illinois and the level of such costs included in electric distribution and natural gas delivery service rates. Pursuant to a June 2020 ICC order, Ameren Illinois’ electric distribution bad debt rider provided for the recovery of bad debt expense in 2020. The under-recovery or over-recovery for each year is recovered from, or refunded to, customers over a twelve-month period beginning June the following year.

(k)Maintenance expenses related to scheduled refueling and maintenance outages at Ameren Missouri’s Callaway Energy Center. Amounts are amortized over the period between refueling and maintenance outages, which has historically been approximately 18 months.

(l)Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.

(m)The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 14 – Commitments and Contingencies for additional information.

(n)Storm costs from 2018, 2020, and 2021 deferred in accordance with the IEIMA. These costs are being amortized over five-year periods beginning in the year the storm occurred.

(o)The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to record an allowance for funds used during construction for pollution control equipment at its Sioux Energy Center until the cost of that equipment was included in customer rates beginning in 2011. These costs are being amortized over the expected life of the Sioux Energy Center through 2028.

(p)Costs associated with Ameren Illinois’ customer generation rebate program. Costs are amortized over a 15-year period, beginning in the year rebates are paid.

(q)Under the PISA, Ameren Missouri is permitted to defer and recover 85% of the depreciation expense and earn a return at the applicable WACC on investments in certain property, plant, and equipment placed in service and not included in base rates. Accumulated PISA deferrals are added to rate base prospectively and amortized over a period of 20 years following a regulatory rate review.

(r)The electric energy-efficiency investments are being amortized over their weighted-average useful lives beginning in the period in which they were made, with current remaining amortization periods ranging from 5 to 13 years.

(s)Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, net of salvage.

(t)The ARO regulatory liability includes the nuclear decommissioning trust fund balance ($1,159 million and $982 million at December 31, 2021 and 2020, respectively), net of recoverable removal costs for AROs ($556 million and $546 million at December 31, 2021 and 2020, respectively). See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations.

(u)Over-recovered costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 10 – Retirement Benefits for additional information.

(v)A regulatory recovery mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri and the level of such costs included in customer rates. The period of refund varies based on MoPSC approval in a regulatory rate review. The weighted-average remaining amortization period is five years.

(w)Funds collected for the purchase of renewable energy credits and zero emission credits through IPA procurements. The balance will be amortized as the credits are purchased.

(x)Over-recovered costs associated with Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard. Under-recovered or over-recovered costs are aggregated over a twelve-month period beginning each August and are amortized over a twelve-month period beginning February the following year.

(y)The excess amount collected in rates related to the TCJA from January 1, 2018, through July 31, 2018. The regulatory liability is being amortized over a three-year period, which began in April 2020.