Debt (Narrative) (Details) - USD ($)		1 Months Ended			3 Months Ended		9 Months Ended
	May 31, 2016	Sep. 30, 2015	Jun. 30, 2015	May 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	May 17, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Net Income (Loss) Attributable to Parent					$ 47,256,000	$ 28,646,000	$ 104,733,000	$ 45,590,000
Long-term Debt					2,498,113,000		2,498,113,000			$ 2,153,276,000
Gains (Losses) on Extinguishment of Debt					0	(2,728,000)	0	(22,051,000)
Proceeds from Issuance of First Mortgage Bond					2,553,500,000		2,553,500,000			2,345,300,000
Line of credit facility, term				5 years
Maximum borrowing capacity				$ 250,000,000
Line of credit facility, accordion feature				$ 150,000,000
Line of credit, outstanding borrowings					25,000,000		$ 25,000,000			75,000,000
Letter of Credit [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date							Oct. 16, 2020
Indianapolis Power And Light Company [Member]
Debt Instrument [Line Items]
Long-term Debt					$ 1,698,899,000		$ 1,698,899,000			1,355,505,000
Indianapolis Power And Light Company [Member] | First Mortgage Bond 4.05% Due May 2046
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond									$ 350,000,000
Debt Instrument, Interest Rate, Stated Percentage	4.05%				4.05%		4.05%
Debt instrument, maturity date							May 01, 2046
Proceeds from Issuance of Secured Debt	$ 343,600,000
Indianapolis Power And Light Company [Member] | First Mortgage Bond Nineteen [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond	350,000,000	$ 260,000,000				$ 260,000,000		$ 260,000,000
Debt Instrument, Interest Rate, Stated Percentage		4.70%			4.70%	4.70%	4.70%	4.70%
Debt instrument, maturity date							Sep. 01, 2045
Proceeds from Issuance of Secured Debt		$ 255,600,000
Parent Company [Member] | Seven Point Two Five Percent Senior Secured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt			$ 33,500,000
Extinguishment of Debt, Amount			$ 366,500,000
Parent Company [Member] | Three Point Four Five Percent Senior Secured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt					$ 405,000,000		$ 405,000,000			$ 405,000,000
Debt Instrument, Interest Rate, Stated Percentage					3.45%		3.45%
Debt instrument, maturity date							Jul. 01, 2020
Debt Instrument, Ratio of Principal to Public Offering Price			99.929%
Proceeds from Issuance of Secured Debt			$ 399,500,000
Other Nonoperating Income (Expense) [Member] | Parent Company [Member] | Seven Point Two Five Percent Senior Secured Notes [Member]
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt			$ (22,100,000)
Medium-term Notes [Member] | Indianapolis Power And Light Company [Member] | Unsecured 364-day Taxable Term Loan [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond	$ 91,900,000
Line of credit facility, term	364 days
Utility Segment [Member]
Debt Instrument [Line Items]
Net Income (Loss) Attributable to Parent					$ 51,900,000	$ 35,200,000	$ 122,000,000	$ 80,200,000