Debt - Non-Recourse Debt Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Debt Instrument [Line Items]
Debt defaults at risk of causing cross default	0
Gain (loss) on extinguishment of debt	$ 4	$ (23)
Proceeds from Lines of Credit	248	$ 101
Parent Company [Member]
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	7
Nonrecourse Debt [Member]
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	(2)
Issued new debt	309
Repayments of Debt	342
Nonrecourse Debt [Member] | IPALCO Enterprises, Inc. [Member]
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	0
Issued new debt	148
Repayments of Debt	83
Nonrecourse Debt [Member] | Other Subsidiaries [Member]
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt	(2)
Issued new debt	161
Repayments of Debt	$ 259