Property And Plant, Net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY AND PLANT, NET

PROPERTY, PLANT, AND EQUIPMENT, NET

The following table presents property, plant, and equipment, net, for each of the Ameren Companies at December 31, 2017 and 2016:

	Ameren Missouri(a)		Ameren Illinois		Other		Ameren(a)
2017
Property, plant, and equipment at original cost:(b)
Electric generation	$	11,132	$	—	$	—	$	11,132
Electric distribution	5,766		5,649		—		11,415
Electric transmission	1,201		2,298		1,167		4,666
Natural gas	474		2,419		—		2,893
Other(c)	922		757		242		1,921
	19,495		11,123		1,409		32,027
Less: Accumulated depreciation and amortization	8,305		3,082		246		11,633
	11,190		8,041		1,163		20,394
Construction work in progress:
Nuclear fuel in process	148		—		—		148
Other	413		252		259		924
Property, plant, and equipment, net	$	11,751	$	8,293	$	1,422	$	21,466
2016
Property, plant, and equipment at original cost:(b)
Electric generation	$	10,911	$	—	$	—	$	10,911
Electric distribution	5,563		5,287		—		10,850
Electric transmission	1,151		2,016		712		3,879
Natural gas	455		2,186		—		2,641
Other(c)	879		719		239		1,837
	18,959		10,208		951		30,118
Less: Accumulated depreciation and amortization	7,880		2,850		231		10,961
	11,079		7,358		720		19,157
Construction work in progress:
Nuclear fuel in process	206		—		—		206
Other	193		111		446		750
Property, plant, and equipment, net	$	11,478	$	7,469	$	1,166	$	20,113

(a) Amounts in Ameren and Ameren Missouri include two CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $233 million and $232 million at December 31, 2017 and 2016, respectively. The total accumulated depreciation associated with the two CTs was $83 million and $77 million at December 31, 2017 and 2016, respectively. See Note 5 – Long-term Debt and Equity Financings for additional information on these capital lease 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) Other property, plant, and equipment includes assets used to support electric and natural gas services.

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 5 to 10 years. The following table presents the gross carrying value of capitalized software, the related accumulated amortization, and the amortization expense of capitalized software by year:

	Amortization Expense(a)						Gross Carrying Value				Accumulated Amortization
	2017		2016		2015		2017		2016		2017			2016
Ameren	$	58	$	52	$	47	$	655	$	622	$	(466	)	$	(408	)
Ameren Missouri	20		17		16		191		178		(107		)	(87		)
Ameren Illinois	36		33		27		241		225		(146		)	(110		)

(a) As of December 31, 2017, the estimated amortization expense of capitalized software for each of the five succeeding years is not expected to differ materially from the current year expense.

The following table provides accrued capital and nuclear fuel expenditures at December 31, 2017, 2016, and 2015, which represent noncash investing activity excluded from the accompanying statements of cash flows:

	Ameren(a)		Ameren Missouri		Ameren Illinois
Accrued capital expenditures:
2017	$	361	$	159	$	175
2016	251		116		87
2015	235		85		92
Accrued nuclear fuel expenditures:
2017	10		10		(b)
2016	20		20		(b)
2015	16		16		(b)

(a) Includes amounts for Ameren registrant and nonregistrant subsidiaries.

(b) Not applicable.