Segment Information (Tables)

12 Months Ended

Dec. 31, 2021

Segment Reporting [Abstract]

Schedule Of Segment Reporting Information, By Segment

The following tables present information about the reported revenue and specified items reflected in net income attributable to common shareholders and capital expenditures by segment at Ameren and Ameren Illinois for the years ended December 31, 2021, 2020, and 2019. Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount.

Ameren

	Ameren Missouri			Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission			Other		Intersegment Eliminations			Ameren
2021
External revenues	$	3,311		$	1,635	$	957	$	491		$	—	$	—		$	6,394
Intersegment revenues	42			4		—		71			—		(117)			—
Depreciation and amortization	632			309		90		111			4		—			1,146
Interest income	26			1		—		—			3		(3)			27
Interest charges	137			74		42		83		(a)	50		(3)			383
Income taxes (benefit)	3			53		39		82			(20)		—			157
Net income (loss) attributable to Ameren common shareholders	518			165		108		230			(31)		—			990
Capital expenditures	2,015		(b)	579		278		616			4		(13)			3,479		(b)
2020
External revenues	$	3,069		$	1,496	$	760	$	469		$	—	$	—		$	5,794
Intersegment revenues	40			2		—		54			—		(96)			—
Depreciation and amortization	604			288		81		98			4		—			1,075
Interest income	26			2		—		1			4		(4)			29
Interest charges	190			72		41		78		(a)	42		(4)			419
Income taxes (benefit)	34			42		36		78			(35)		—			155
Net income (loss) attributable to Ameren common shareholders	436			143		99		216			(23)		—			871
Capital expenditures	1,666		(b)	543		301		716			5		2			3,233		(b)
2019
External revenues	$	3,212		$	1,487	$	791	$	401		$	—	$	—		$	5,891
Intersegment revenues	31			17		6		63			—		(98)			19		(c)
Depreciation and amortization	556			273		78		84			4		—			995
Interest income	26			6		—		1			5		(5)			33
Interest charges	178			71		38		74		(a)	25		(5)			381
Income taxes (benefit)	68			45		30		64			(25)		—			182
Net income (loss) attributable to Ameren common shareholders	426			146		84		185			(13)		—			828
Capital expenditures	1,076			518		318		528			3		(32)		(d)	2,411

(a)Ameren Transmission interest charges include an allocation of financing costs from Ameren (parent).

(b)Includes $525 million and $564 million at Ameren and Ameren Missouri for wind generation expenditures for the year ended December 31, 2021 and 2020, respectively.

(c)Intersegment revenues at Ameren include $14 million and $5 million of revenue from Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas, respectively, for the year ended December 31, 2019, for a software licensing agreement with Ameren Missouri. Under authoritative accounting guidance for rate-regulated entities, the revenue recognized by Ameren Illinois was not eliminated upon consolidation. See Note 13 – Related-party Transactions for additional information.

(d)Intersegment capital expenditure eliminations include $24 million of eliminations for the year ended December 31, 2019, for a software licensing agreement between Ameren Illinois and Ameren Missouri. See Note 13 – Related-party Transactions for additional information.

Ameren Illinois

	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
2021
External revenues	$	1,639	$	957	$	299	$	—	$	2,895
Intersegment revenues	—		—		66		(66)		—
Depreciation and amortization	309		90		73		—		472
Interest income	1		—		—		—		1
Interest charges	74		42		48		—		164
Income taxes	53		39		51		—		143
Net income available to common shareholder	165		108		152		—		425
Capital expenditures	579		278		575		—		1,432
2020
External revenues	$	1,498	$	760	$	277	$	—	$	2,535
Intersegment revenues	—		—		52		(52)		—
Depreciation and amortization	288		81		65		—		434
Interest income	2		—		1		—		3
Interest charges	72		41		42		—		155
Income taxes	42		36		46		—		124
Net income available to common shareholder	143		99		137		—		379
Capital expenditures	543		301		603		—		1,447
2019
External revenues	$	1,504	$	797	$	226	$	—	$	2,527
Intersegment revenues	—		—		62		(62)		—
Depreciation and amortization	273		78		55		—		406
Interest income	6		—		—		—		6
Interest charges	71		38		38		—		147
Income taxes	45		30		35		—		110
Net income available to common shareholder	146		84		113		—		343
Capital expenditures	518		318		372		—		1,208

Disaggregation of Revenue

The following tables present disaggregated revenues by segment at Ameren and Ameren Illinois for the years ended December 31, 2021, 2020, and 2019. Economic factors affect the nature, timing, amount, and uncertainty of revenues and cash flows in a similar manner across customer classes. Revenues from alternative revenue programs have a similar distribution among customer classes as revenues from contracts with customers. Other revenues not associated with contracts with customers are presented in the Other customer classification, along with electric transmission and off-system revenues.

Ameren

	Ameren Missouri		Ameren Illinois Electric Distribution			Ameren Illinois Natural Gas			Ameren Transmission		Intersegment Eliminations		Ameren
2021
Residential	$	1,445	$	933		$	—		$	—	$	—	$	2,378
Commercial	1,126		545			—			—		—		1,671
Industrial	280		135			—			—		—		415
Other	361		26			—			562		(116)		833
Total electric revenues	$	3,212	$	1,639		$	—		$	562	$	(116)	$	5,297
Residential	$	79	$	—		$	657		$	—	$	—	$	736
Commercial	34		—			172			—		—		206
Industrial	4		—			35			—		—		39
Other	24		—			93			—		(1)		116
Total gas revenues	$	141	$	—		$	957		$	—	$	(1)	$	1,097
Total revenues(a)	$	3,353	$	1,639		$	957		$	562	$	(117)	$	6,394
2020
Residential	$	1,373	$	867		$	—		$	—	$	—	$	2,240
Commercial	1,025		486			—			—		—		1,511
Industrial	261		124			—			—		—		385
Other	325		21			—			523		(94)		775
Total electric revenues	$	2,984	$	1,498		$	—		$	523	$	(94)	$	4,911
Residential	$	76	$	—		$	541		$	—	$	—	$	617
Commercial	29		—			136			—		—		165
Industrial	4		—			14			—		—		18
Other	16		—			69			—		(2)		83
Total gas revenues	$	125	$	—		$	760		$	—	$	(2)	$	883
Total revenues(a)	$	3,109	$	1,498		$	760		$	523	$	(96)	$	5,794
2019
Residential	$	1,403	$	848		$	—		$	—	$	—	$	2,251
Commercial	1,157		497			—			—		—		1,654
Industrial	278		127			—			—		—		405
Other	271		32		(b)	—			464		(96)		671
Total electric revenues	$	3,109	$	1,504		$	—		$	464	$	(96)	$	4,981
Residential	$	81	$	—		$	570		$	—	$	—	$	651
Commercial	34		—			154			—		—		188
Industrial	4		—			13			—		—		17
Other	15		—			60		(b)	—		(2)		73
Total gas revenues	$	134	$	—		$	797		$	—	$	(2)	$	929
Total revenues(a)	$	3,243	$	1,504		$	797		$	464	$	(98)	$	5,910

(a)The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the years ended December 31, 2021, 2020, and 2019:

	Ameren Missouri			Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission		Ameren
2021
Revenues from alternative revenue programs	$	(16)		$	77	$	5	$	11	$	77
Other revenues not from contracts with customers	56		(a)	10		2		—		68		(a)
2020
Revenues from alternative revenue programs	$	(14)		$	(20)	$	20	$	50	$	36
Other revenues not from contracts with customers	25			8		2		1		36
2019
Revenues from alternative revenue programs	$	35		$	(74)	$	—	$	(31)	$	(70)
Other revenues not from contracts with customers	19			7		2		—		28

(a)Includes insurance recoveries related to lost sales associated with the Callaway Energy Center maintenance outage. See Note 9 – Callaway Energy Center for additional information.

(b)Includes $14 million and $5 million for Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas, respectively, for the year ended December 31, 2019, for a software licensing agreement with Ameren Missouri. See Note 13 – Related-party Transactions for additional information.

Ameren Illinois

	Ameren Illinois Electric Distribution			Ameren Illinois Natural Gas			Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
2021
Residential	$	933		$	657		$	—	$	—	$	1,590
Commercial	545			172			—		—		717
Industrial	135			35			—		—		170
Other	26			93			365		(66)		418
Total revenues(a)	$	1,639		$	957		$	365	$	(66)	$	2,895
2020
Residential	$	867		$	541		$	—	$	—	$	1,408
Commercial	486			136			—		—		622
Industrial	124			14			—		—		138
Other	21			69			329		(52)		367
Total revenues(a)	$	1,498		$	760		$	329	$	(52)	$	2,535
2019
Residential	$	848		$	570		$	—	$	—	$	1,418
Commercial	497			154			—		—		651
Industrial	127			13			—		—		140
Other	32		(b)	60		(b)	288		(62)		318
Total revenues(a)	$	1,504		$	797		$	288	$	(62)	$	2,527

(a)The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the Ameren Illinois segments for the years ended December 31, 2021, 2020, and 2019:

	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Ameren Illinois
2021
Revenues from alternative revenue programs	$	77	$	5	$	9	$	91
Other revenues not from contracts with customers	10		2		—		12
2020
Revenues from alternative revenue programs	$	(20)	$	20	$	42	$	42
Other revenues not from contracts with customers	8		2		—		10
2019
Revenues from alternative revenue programs	$	(74)	$	—	$	(33)	$	(107)
Other revenues not from contracts with customers	7		2		—		9

(b)Includes $14 million and $5 million for Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas, respectively, for the year ended December 31, 2019, for a software licensing agreement with Ameren Missouri. See Note 13 – Related-party Transactions for additional information.