Property And Plant, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Schedule Of Property And Plant, Net

The following table presents property, plant, and equipment, net, at December 31, 2020 and 2019:

	Ameren Missouri(a)		Ameren Illinois		Other		Ameren(a)
2020
Property, plant, and equipment at original cost:(b)
Electric generation:
Coal(c)	$	4,875	$	—	$	—	$	4,875
Natural gas and oil	1,097		—		—		1,097
Nuclear	5,608		—		—		5,608
Renewable(d)	1,301		—		—		1,301
Electric distribution	6,784		6,649		—		13,433
Electric transmission	1,482		3,575		1,774		6,831
Natural gas	561		3,308		—		3,869
Other(e)	1,390		1,070		245		2,705
	23,098		14,602		2,019		39,719
Less: Accumulated depreciation and amortization	9,689		3,780		304		13,773
	13,409		10,822		1,715		25,946
Construction work in progress:
Nuclear fuel in process	75		—		—		75
Other	395		379		12		786
Property, plant, and equipment, net	$	13,879	$	11,201	$	1,727	$	26,807
2019
Property, plant, and equipment at original cost:(b)
Electric generation:
Coal(c)	$	4,730	$	—	$	—	$	4,730
Natural gas and oil	1,090		—		—		1,090
Nuclear	5,414		—		—		5,414
Renewable(d)	646		—		—		646
Electric distribution	6,371		6,299		—		12,670
Electric transmission	1,405		3,101		1,642		6,148
Natural gas	528		3,024		—		3,552
Other(e)	1,173		993		236		2,402
	21,357		13,417		1,878		36,652
Less: Accumulated depreciation and amortization	9,195		3,536		275		13,006
	12,162		9,881		1,603		23,646
Construction work in progress:
Nuclear fuel in process	135		—		—		135
Other	338		202		55		595
Property, plant, and equipment, net	$	12,635	$	10,083	$	1,658	$	24,376

(a)Amounts include two CTs that have related financing obligations. The gross cumulative asset value of those agreements was $240 million and $236 million at December 31, 2020 and 2019, respectively. The total accumulated depreciation associated with the two CTs was $99 million and $95 million at December 31, 2020 and 2019, respectively. See Note 5 – Long-term Debt and Equity Financings for additional information on these agreements.

(b)The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri’s hydro generating assets, which have useful lives of up to 150 years, 20 to 80 years for electric distribution, 50 to 75 years for electric transmission, 20 to 80 years for natural gas, and 5 to 55 years for other.

(c)Includes $36 million of oil-fired generation in both 2019 and 2020.

(d)Renewable includes hydroelectric, wind, solar, and methane gas generation facilities.

(e)Other property, plant, and equipment includes assets used to support electric and natural gas services.

Schedule of Capitalized Software

Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 3 to 10 years. The following table presents the amortization, gross carrying value, and related accumulated amortization of capitalized software by year:

	Amortization Expense						Gross Carrying Value				Accumulated Amortization
	2020		2019		2018		2020		2019		2020		2019
Ameren	$	93	$	78	$	71	$	1,021	$	901	$	(640)	$	(584)
Ameren Missouri	44		30		24		398		303		(189)		(153)
Ameren Illinois	45		45		44		397		377		(238)		(221)

Schedule of Capitalized Software, Future Amortization Expense

Annual amortization expense for capitalized costs for software placed in service as of December 31, 2020, is estimated to be as follows:

	2021		2022		2023		2024		2025
Ameren	$	105	$	94	$	81	$	55	$	23
Ameren Missouri	55		49		45		33		15
Ameren Illinois	46		42		34		21		7