Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2017

Accounting Policies [Abstract]

Summary Of Nonvested Shares Related To Long-Term Incentive Plan

A summary of nonvested performance share units at March 31, 2017, and changes during the three months ended March 31, 2017, under the 2014 Incentive Plan are presented below:

	Performance Share Units
	Share Units		Weighted-average Fair Value per Share Unit
Nonvested at January 1, 2017	1,059,639		$	48.04
Granted(a)	496,068		59.16
Forfeitures	(3,192	)	49.13
Vested(b)	(3,779	)	52.88
Nonvested at March 31, 2017	1,548,736		$	51.59

(a) Performance share units granted to certain executive and nonexecutive officers and other eligible employees under the 2014 Incentive Plan.

(b) Performance share units vested due to the attainment of retirement eligibility by certain employees. Actual shares issued for retirement-eligible employees vary depending on actual performance over the three-year measurement period.

Schedule of Excise Taxes

The following table presents excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” for the three months ended March 31, 2017 and 2016:

	Three Months
	2017		2016
Ameren Missouri	$	31	$	30
Ameren Illinois	19		20
Ameren	$	50	$	50