Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2021

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Open Gross Derivative Volumes By Commodity Type

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of June 30, 2021, and December 31, 2020. As of June 30, 2021, these contracts extended through October 2023, October 2026, and May 2032 for fuel oils, natural gas and power, respectively.

	Quantity (in millions)
	June 30, 2021			December 31, 2020
Commodity	Ameren Missouri	Ameren Illinois	Ameren	Ameren Missouri	Ameren Illinois	Ameren
Fuel oils (in gallons)	30	—	30	43	—	43
Natural gas (in mmbtu)	33	118	151	33	114	147
Power (in MWhs)	6	7	13	6	7	13

Derivative Instruments Carrying Value

The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of June 30, 2021, and December 31, 2020:

			June 30, 2021					December 31, 2020
	Balance Sheet Location		Ameren Missouri		Ameren Illinois		Ameren			Ameren Missouri		Ameren Illinois		Ameren
Fuel oils	Other current assets	$	7	$	—	$	7		$	2	$	—	$	2
	Other assets		5		—		5			—		—		—
Natural gas	Other current assets		7		26		33			1		8		9
	Other assets		3		10		13			2		2		4
Power	Other current assets		15		—		15			7		—		7
	Other assets		1		—		1			—		—		—
	Total assets	$	38	$	36	$	74		$	12	$	10	$	22
Fuel oils	Other current liabilities	$	1	$	—	$	1		$	7	$	—	$	7
	Other deferred credits and liabilities		—		—		—			2		—		2
Natural gas	Other current liabilities		—		1		1			1		1		2
	Other deferred credits and liabilities		—		—		—			—		1		1
Power	Other current liabilities		27		12		39			3		17		20
	Other deferred credits and liabilities		17		154		171			8		181		189
	Total liabilities	$	45	$	167	$	212		$	21	$	200	$	221