Retirement Benefits

3 Months Ended

Mar. 31, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

RETIREMENT BENEFITS

RETIREMENT BENEFITS

Ameren’s pension plans are funded in compliance with income tax regulations and to meet federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren’s assumptions at March 31, 2016, the plan’s estimated investment performance through March 31, 2016, and Ameren’s pension funding policy, Ameren expects to make annual contributions of $40 million to $70 million through 2020, with aggregate estimated contributions of $280 million. These amounts are estimates which may change with actual investment performance, changes in interest rates, any pertinent changes in government regulations, and any voluntary contributions. Separately, our policy for postretirement benefits is primarily to fund the voluntary employees’ beneficiary association trusts to match the annual postretirement expense.

The following table presents the components of the net periodic benefit cost (benefit) incurred for Ameren’s pension and postretirement benefit plans for the three months ended March 31, 2016 and 2015:

	Pension Benefits						Postretirement Benefits
	Three Months						Three Months
	2016			2015			2016			2015
Service cost	$	20		$	24		$	5		$	5
Interest cost	47			44			12			12
Expected return on plan assets	(63		)	(62		)	(18		)	(17		)
Amortization of:
Prior service benefit	—			—			(1		)	(1		)
Actuarial loss (gain)	9			18			(3		)	1
Net periodic benefit cost (benefit)	$	13		$	24		$	(5	)	$	—

Ameren Missouri and Ameren Illinois are responsible for their respective shares of Ameren’s pension and postretirement costs. The following table presents the pension costs and the postretirement benefit costs (benefit) incurred for the three months ended March 31, 2016 and 2015:

	Pension Benefits				Postretirement Benefits
	Three Months				Three Months
	2016		2015		2016			2015
Ameren Missouri(a)	$	8	$	15	$	(1	)	$	1
Ameren Illinois	5		9		(4		)	(1		)
Ameren(a)(b)	$	13	$	24	$	(5	)	$	—

(a) Does not include the impact of the regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates.

(b) Includes amounts for Ameren registrants and nonregistrant subsidiaries.