Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2018 and 2017:



		December 31, 2018									December 31, 2017
		Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
Assets:
Ameren
	Derivative assets – commodity contracts^(a):
	Fuel oils	$	1	$	—	$	7	$	8		$	4	$	—	$	3	$	7
	Natural gas	—		2		1		3			—		—		1		1
	Power	—		1		3		4			—		1		8		9
	Total derivative assets – commodity contracts	$	1	$	3	$	11	$	15		$	4	$	1	$	12	$	17
	Nuclear decommissioning trust fund:
	Equity securities:
	U.S. large capitalization	$	427	$	—	$	—	$	427		$	468	$	—	$	—	$	468
	Debt securities:
	U.S. Treasury and agency securities	—		148		—		148			—		125		—		125
	Corporate bonds	—		72		—		72			—		82		—		82
	Other	—		32		—		32			—		25		—		25
	Total nuclear decommissioning trust fund	$	427	$	252	$	—	$	679	^(b)	$	468	$	232	$	—	$	700	^(b)
	Total Ameren	$	428	$	255	$	11	$	694		$	472	$	233	$	12	$	717
Ameren Missouri
	Derivative assets – commodity contracts^(a):
	Fuel oils	$	1	$	—	$	7	$	8		$	4	$	—	$	3	$	7
	Natural gas	—		—		—		—			—		—		1		1
	Power	—		1		3		4			—		1		8		9
	Total derivative assets – commodity contracts	$	1	$	1	$	10	$	12		$	4	$	1	$	12	$	17
	Nuclear decommissioning trust fund:
	Equity securities:
	U.S. large capitalization	$	427	$	—	$	—	$	427		$	468	$	—	$	—	$	468
	Debt securities:
	U.S. Treasury and agency securities	—		148		—		148			—		125		—		125
	Corporate bonds	—		72		—		72			—		82		—		82
	Other	—		32		—		32			—		25		—		25
	Total nuclear decommissioning trust fund	$	427	$	252	$	—	$	679	^(b)	$	468	$	232	$	—	$	700	^(b)
	Total Ameren Missouri	$	428	$	253	$	10	$	691		$	472	$	233	$	12	$	717
Ameren Illinois
	Derivative assets – commodity contracts^(a):
	Natural gas	$	—	$	2	$	1	$	3		$	—	$	—	$	—	$	—
Liabilities:
Ameren
	Derivative liabilities – commodity contracts^(a):
	Fuel oils	$	2	$	—	$	11	$	13		$	—	$	—	$	—	$	—
	Natural gas	—		15		4		19			1		25		4		30
	Power	—		1		186		187			—		—		196		196
	Total Ameren	$	2	$	16	$	201	$	219		$	1	$	25	$	200	$	226
Ameren Missouri
	Derivative liabilities – commodity contracts^(a):
	Fuel oils	$	2	$	—	$	11	$	13		$	—	$	—	$	—	$	—
	Natural gas	—		5		—		5			—		7		1		8
	Power	—		1		3		4			—		—		1		1
	Total Ameren Missouri	$	2	$	6	$	14	$	22		$	—	$	7	$	2	$	9
Ameren Illinois
	Derivative liabilities – commodity contracts^(a):
	Natural gas	$	—	$	10	$	4	$	14		$	1	$	18	$	3	$	22
	Power	—		—		183		183			—		—		195		195
	Total Ameren Illinois	$	—	$	10	$	187	$	197		$	1	$	18	$	198	$	217


(a)	The derivative asset and liability balances are presented net of registrant and counterparty credit considerations.


(b)	Balance excludes $5 million and $4 million of cash and cash equivalents, receivables, payables, and accrued income, net for December 31, 2018 and 2017, respectively.

Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy

The following table presents the fair value reconciliation of Level 3 power derivative contract assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2018 and 2017:



	2018									2017
	Ameren Missouri			Ameren Illinois			Ameren			Ameren Missouri			Ameren Illinois			Ameren
Beginning balance at January 1	$	7		$	(195	)	$	(188	)	$	7		$	(185	)	$	(178	)
Realized and unrealized gains (losses) included in regulatory assets/liabilities	(6		)	—			(6		)	(4		)	(21		)	(25		)
Purchases	5			—			5			14			—			14
Sales	—			—			—			1			—			1
Settlements	(5		)	12			7			(11		)	11			—
Transfers out of Level 3	(1		)	—			(1		)	—			—			—
Ending balance at December 31	$	—		$	(183	)	$	(183	)	$	7		$	(195	)	$	(188	)
Change in unrealized gains (losses) related to assets/liabilities held at December 31	$	(1	)	$	(2	)	$	(3	)	$	—		$	(22	)	$	(22	)

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]

The following table sets forth, by level within the fair value hierarchy, the carrying amount and fair value of financial assets and liabilities disclosed, but not carried, at fair value as of December 31, 2018 and 2017:



	December 31, 2018
	Carrying Amount			Fair Value
	Carrying Amount			Level 1		Level 2		Level 3			Total
Ameren:
Cash, cash equivalents, and restricted cash	$	107		$	107	$	—	$	—		$	107
Investments in held-to-maturity debt securities^(a)	270			—		270		—			270
Short-term debt	597			—		597		—			597
Long-term debt (including current portion)^(a)	8,439		^(b)	—		8,240		429		^(c)	8,669
Ameren Missouri:
Cash, cash equivalents, and restricted cash	$	8		$	8	$	—	$	—		$	8
Investments in held-to-maturity debt securities^(a)	270			—		270		—			270
Short-term debt	55			—		55		—			55
Long-term debt (including current portion)^(a)	3,998		^(b)	—		4,156		—			4,156
Ameren Illinois:
Cash, cash equivalents, and restricted cash	$	80		$	80	$	—	$	—		$	80
Short-term debt	72			—		72		—			72
Long-term debt (including current portion)	3,296		^(b)	—		3,391		—			3,391
	December 31, 2017
Ameren:
Cash, cash equivalents, and restricted cash	$	68		$	68	$	—	$	—		$	68
Investments in held-to-maturity debt securities^(a)	276			—		276		—			276
Short-term debt	484			—		484		—			484
Long-term debt (including current portion)^(a)	7,935		^(b)	—		8,531		—			8,531
Ameren Missouri:
Cash, cash equivalents, and restricted cash	$	7		$	7	$	—	$	—		$	7
Investments in held-to-maturity debt securities^(a)	276			—		276		—			276
Short-term debt	39			—		39		—			39
Long-term debt (including current portion)^(a)	3,961		^(b)	—		4,348		—			4,348
Ameren Illinois:
Cash, cash equivalents, and restricted cash	$	41		$	41	$	—	$	—		$	41
Short-term debt	62			—		62		—			62
Long-term debt (including current portion)	2,830		^(b)	—		3,028		—			3,028

(a)

Ameren and Ameren Missouri have investments in industrial development revenue bonds, classified as held-to-maturity and recorded in “Other Assets,” that are equal to the finance obligations for the Peno Creek and Audrain CT energy centers. As of December 31, 2018 and 2017, the carrying amount of both the investments in industrial development revenue bonds and the finance obligations approximated fair value.

(b)

Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $58 million, $22 million, and $31 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2018. Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $50 million, $20 million, and $24 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2017.


(c)	The Level 3 fair value amount consists of ATXI’s senior unsecured notes. In the first quarter of 2018, the amount was transferred to Level 3 because inputs to the valuation model became unobservable during the period.

Fair Value Inputs, Assets and Liabilities, Quantitative Information

The following table describes the valuation techniques and significant unobservable inputs utilized for the fair value of our Level 3 power derivative contract assets and liabilities as of December 31, 2018 and 2017:



		Fair Value^(a)								Weighted
	Commodity	Assets		Liabilities			Valuation Technique(s)	Unobservable Input	Range	Average
2018	Power^(b)	$	3	$	(186	)	Discounted cash flow	Average forward peak and off-peak pricing – forwards/swaps($/MWh)^(c)	23 – 39	28
								Nodal basis($/MWh)^(c)	(9) – 0	(2)
							Fundamental energy production model	Estimated future natural gas prices($/mmbtu)^(c)	3 – 4	3
								Escalation rate(%)^(c)(d)	4 – 5	4
2017	Power^(b)	$	8	$	(196	)	Discounted cash flow	Average forward peak and off-peak pricing – forwards/swaps($/MWh)^(c)	24 – 46	28
								Nodal basis($/MWh)^(c)	(10) – 0	(2)
							Fundamental energy production model	Estimated future natural gas prices($/mmbtu)^(c)	3 – 4	3
								Escalation rate(%)^(c)(d)	5	5

(a)The derivative asset and liability balances are presented net of registrant and counterparty credit considerations.


(b)	Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2022 and 2021 for December 31, 2018 and 2017, respectively. Valuations beyond 2022 and 2021 for December 31, 2018 and 2017, respectively, use fundamentally modeled pricing by month for peak and off-peak demand.


(c)	Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.


(d)	Escalation rate applies to power prices in 2031 and beyond.