Property And Plant, Net (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule Of Property And Plant, Net

The following table presents property, plant, and equipment, net, for each of the Ameren Companies at December 31, 2016 and 2015:

	Ameren Missouri(a)		Ameren Illinois		Other		Ameren(a)
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 and plant, net	$	11,478	$	7,469	$	1,166	$	20,113
2015
Property, plant, and equipment at original cost:(b)
Electric generation	$	10,431	$	—	$	—	$	10,431
Electric distribution	5,303		4,952		—		10,255
Electric transmission	979		1,674		121		2,774
Natural gas	445		1,997		—		2,442
Other(c)	808		627		266		1,701
	17,966		9,250		387		27,603
Less: Accumulated depreciation and amortization	7,460		2,632		255		10,347
	10,506		6,618		132		17,256
Construction work in progress:
Nuclear fuel in process	275		—		—		275
Other	402		230		636		1,268
Property, plant, and equipment, net	$	11,183	$	6,848	$	768	$	18,799

(a) Amounts in Ameren and Ameren Missouri include two CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $232 million and $233 million at December 31, 2016 and 2015, respectively. The total accumulated depreciation associated with the two CTs was $77 million and $72 million at December 31, 2016 and 2015, respectively. In addition, Ameren Missouri has investments in debt securities, classified as held-to-maturity and recorded in "Other assets" that are related to the two CTs from the city of Bowling Green and Audrain County. As of December 31, 2016 and 2015, the carrying value of these debt securities was $282 million and $288 million, respectively.

(b) The estimated lives for each asset group are as follows: 5 to 100 years for electric generation, excluding Ameren Missouri's hydro generating assets which have useful lives of up to 150 years, 18 to 75 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 multiple utility services.

Accrued Capital Expenditures

The following table provides accrued capital and nuclear fuel expenditures at December 31, 2016, 2015, and 2014, which represent noncash investing activity excluded from the accompanying statements of cash flows:

	Ameren(a)		Ameren Missouri		Ameren Illinois
Accrued capital expenditures:
2016	$	251	$	116	$	87
2015	235		85		92
2014	181		72		59
Accrued nuclear fuel expenditures:
2016	20		20		(b)
2015	16		16		(b)
2014	13		13		(b)

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

(b) Not applicable.