Long-Term Debt And Equity Financings Long-Term Debt and Equity Financings (Schedule of Debt Redemptions (Details) (Ameren Illinois Company, USD $)		1 Months Ended
	Mar. 31, 2014	Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member]	Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series1993590 Due2023 [Member]		Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series1994A 570 Due 2024 [Member]		Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series C11993595 Due2026 [Member]	Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series C21993570 Due2026 [Member]	Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series1998A 5 Point 40 Due 2028 [Member]	Jan. 31, 2014 Environmental Improvement And Pollution Control Revenue Bonds [Member] Series1998b540 Due2028 [Member]
Long-Term Debt And Equity Financings [Line Items]
Debt Instrument, Face Amount	$ 1,000,000
Redemptions of Long-term Debt		$ 163,000,000	$ 32,000,000	[1]	$ 36,000,000	[1]	$ 35,000,000	$ 8,000,000	$ 19,000,000	$ 33,000,000

[1] Less than $1 million principal amount of the bonds remain outstanding after redemption