Indebtedness (Schedule Long-Term Indebtedness) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Unamortized discount - net	$ (4,200)		$ (5,000)
Long-term debt	1,761,120		1,760,316
Less: Current Portion of Long-term Debt	110,000
Long-term debt	1,651,120		1,760,316
Ipalco Enterprises, Inc. [Member]
Debt Instrument [Line Items]
Unamortized discount - net	(3,084)		(3,859)
Long-term debt	796,916		796,141
Long-term debt	796,916		796,141
Ipalco Enterprises, Inc. [Member] | 7.250% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Long-term debt	400,000		400,000
Debt, stated interest rate	7.25%
Debt due date	Apr. 01, 2016
Ipalco Enterprises, Inc. [Member] | 5.000% Senior Secured Notes [Member]
Debt Instrument [Line Items]
Long-term debt	400,000		400,000
Debt, stated interest rate	5.00%
Debt due date	May 01, 2018
Indianapolis Power And Light Company [Member]
Debt Instrument [Line Items]
First mortgage bonds	964,204		964,175
Unamortized discount - net	(1,096)		(1,125)
Long-term debt	964,204		964,175
Long-term debt	854,204		964,175
Indianapolis Power And Light Company [Member] | First Mortgage Bond 6.30% Due July 2013 [Member]
Debt Instrument [Line Items]
First mortgage bonds	110,000		110,000
Debt, stated interest rate	6.30%
Debt due date	Jul. 01, 2013
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.90% Due January 2016 [Member]
Debt Instrument [Line Items]
First mortgage bonds	30,000	[1]	30,000	[1]
Debt, stated interest rate	4.90%
Debt due date	Jan. 01, 2016	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.90% Due January 2016 [Member]
Debt Instrument [Line Items]
First mortgage bonds	41,850	[1]	41,850	[1]
Debt, stated interest rate	4.90%
Debt due date	Jan. 01, 2016	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.90% Due January 2016 [Member]
Debt Instrument [Line Items]
First mortgage bonds	60,000	[1]	60,000	[1]
Debt, stated interest rate	4.90%
Debt due date	Jan. 01, 2016	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 5.40% Due August 2017 [Member]
Debt Instrument [Line Items]
First mortgage bonds	24,650	[2]	24,650	[2]
Debt, stated interest rate	5.40%
Debt due date	Aug. 01, 2017	[2]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 3.875% Due August 2021 [Member]
Debt Instrument [Line Items]
First mortgage bonds	55,000	[1]	55,000	[1]
Debt, stated interest rate	3.875%
Debt due date	Aug. 01, 2021	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 3.875% Due August 2021 [Member]
Debt Instrument [Line Items]
First mortgage bonds	40,000	[1]	40,000	[1]
Debt, stated interest rate	3.875%
Debt due date	Aug. 01, 2021	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.55% Due December 2024 [Member]
Debt Instrument [Line Items]
First mortgage bonds	40,000	[1]	40,000	[1]
Debt, stated interest rate	4.55%
Debt due date	Dec. 01, 2024	[1]
Indianapolis Power And Light Company [Member] | First Mortgage Bond 6.60% Due January 2034 [Member]
Debt Instrument [Line Items]
First mortgage bonds	100,000		100,000
Debt, stated interest rate	6.60%
Debt due date	Jan. 01, 2034
Indianapolis Power And Light Company [Member] | First Mortgage Bond 6.05% Due October 2036 [Member]
Debt Instrument [Line Items]
First mortgage bonds	158,800		158,800
Debt, stated interest rate	6.05%
Debt due date	Oct. 01, 2036
Indianapolis Power And Light Company [Member] | First Mortgage Bond 6.60% Due June 2037 [Member]
Debt Instrument [Line Items]
First mortgage bonds	165,000		165,000
Debt, stated interest rate	6.60%
Debt due date	Jun. 01, 2037
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.875% Due November 2041 [Member]
Debt Instrument [Line Items]
First mortgage bonds	$ 140,000		$ 140,000
Debt, stated interest rate	4.875%
Debt due date	Nov. 01, 2041

[1] First Mortgage Bonds are issued to the Indiana Finance Authority, to secure the loan of proceeds from the tax-exempt bonds issued by the Indiana Finance Authority

[2] First Mortgage Bonds are issued to the city of Petersburg, Indiana, to secure the loan of proceeds from various tax-exempt instruments issued by the city.