Long-Term Debt And Equity Financings (Schedule Of Maturities Of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
2014	$ 534
2015	120
2016	395
2017	681
2018	840
Thereafter	3,478
Total	6,048
Parent Company
Debt Instrument [Line Items]
2014	425
2015
2016
2017
2018
Thereafter
Total	425
Unamortized discount and premium			1
Union Electric Company
Debt Instrument [Line Items]
2014	109	[1]
2015	120	[1]
2016	266	[1]
2017	431	[1]
2018	383	[1]
Thereafter	2,455	[1]
Total	3,764	[1]
Unamortized discount and premium	7		7
Ameren Illinois Company
Debt Instrument [Line Items]
2014		[1],[2]
2015		[1],[2]
2016	129	[1],[2]
2017	250	[1],[2]
2018	457	[1],[2]
Thereafter	1,023	[1],[2]
Total	1,859	[1],[2]
Unamortized discount and premium	7		6
Fair value adjustments	$ 4

[1] Excludes unamortized discount and premium of $7 million and $7 million at Ameren Missouri and Ameren Illinois, respectively.

[2] Excludes $4 million related to Ameren Illinois’ long-term debt fair-market value adjustments, which are being amortized to interest expense over the remaining life of the debt.