Impairment and Other Charges (Tables)

12 Months Ended

Dec. 31, 2012

Goodwill and Intangible Assets Disclosure [Abstract]

Impairment Charges

The following table summarizes the pretax charges recognized for the years ended December 31, 2012, 2011, and 2010:

	Long-Lived Assets and Related Charges		Goodwill		Emission Allowances		Total
2012
Ameren(a)	$	2,578	$	—	$	—	$	2,578
2011
Ameren(a)	123		—		2		125
Ameren Missouri	89		—		—		89
2010
Ameren(a)	101		420		68		589

(a) Includes amounts for registrant and nonregistrant subsidiaries.