Redeemable Stock of Subsidiaries (Narrative) (Details)			1 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended
		Feb. 11, 2015 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Feb. 28, 2015 USD ($)	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2017 USD ($) quarter series $ / shares	Dec. 31, 2016 USD ($) quarter $ / shares		Dec. 31, 2015 USD ($)		Sep. 30, 2016 USD ($)	Apr. 01, 2015 USD ($)
Temporary Equity [Line Items]
Temporary Equity, Accretion to Redemption Value								$ 25,000,000	$ 4,000,000
Gain (Loss) on Disposition of Stock in Subsidiary							$ 0
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners								6.70%
Temporary equity carrying amount								$ 837,000,000	782,000,000		$ 538,000,000
Temporary Equity, Stock Issued During Period, Value, New Issues								0	134,000,000
Temporary Equity, Other Changes								50,000,000	130,000,000
Temporary Equity, Net Income								(14,000,000)	11,000,000
Colon [Domain]
Temporary Equity [Line Items]
Temporary Equity, Accretion to Redemption Value									1,000,000
Temporary equity carrying amount								159,000,000	100,000,000
Temporary Equity, Other Changes								50,000,000	106,000,000
IPALCO Enterprises, Inc. [Member]
Temporary Equity [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners				30.00%		30.00%
Temporary equity carrying amount								618,000,000	618,000,000
Temporary Equity, Stock Issued During Period, Value, New Issues				$ 134,000,000
Temporary Equity, Other Changes			$ 24,000,000
IPL Subsidiary
Temporary Equity [Line Items]
Temporary equity carrying amount								$ 60,000,000	60,000,000
Number of preferred stock series | series								5
Temporary equity annual dividend requirement								$ 3,000,000	$ 3,000,000
Number of consecutive quarters without paid dividends to invoke board of directors election rule | quarter								4	4
IPL Subsidiary | Minimum
Temporary Equity [Line Items]
Temporary equity, redemption price per share | $ / shares								$ 100	$ 100
IPL Subsidiary | Maximum
Temporary Equity [Line Items]
Temporary equity, redemption price per share | $ / shares								118	$ 118
DPL Subsidiary
Temporary Equity [Line Items]
Temporary Equity, Accretion to Redemption Value									$ 5,000,000
Temporary equity carrying amount									18,000,000
Temporary equity annual dividend requirement
Number of quarters cumulative dividends in arrears to invoke board of directors election rule | quarter
DPL Subsidiary | Minimum
Temporary Equity [Line Items]
Temporary equity, redemption price per share | $ / shares
DPL Subsidiary | Maximum
Temporary Equity [Line Items]
Temporary equity, redemption price per share | $ / shares
Other Entity [Member]
Temporary Equity [Line Items]
Temporary equity carrying amount								$ 0	$ 4,000,000
AES US Investment, Inc. [Member]
Temporary Equity [Line Items]
Sale of Stock, Consideration Received Per Transaction		$ 247,000,000
Investment In Affiliate Ownership Percentage Sold		15.00%
IPALCO Enterprises, Inc. [Member]
Temporary Equity [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners														24.90%
sales agreement, Buyer option to purchase ownership interest, exercised														$ 214,000,000
Additional Paid-in Capital [Member]
Temporary Equity [Line Items]
Temporary Equity, Net Income	[1]							0	0
Sale of subsidiary shares to noncontrolling interests								13,000,000	84,000,000		323,000,000
Additional Paid-in Capital [Member] | IPALCO Enterprises, Inc. [Member]
Temporary Equity [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Issuance Costs Not Expensed							84,000,000
Retained Earnings [Member]
Temporary Equity [Line Items]
Temporary Equity, Net Income	[1]							0	0
Sale of subsidiary shares to noncontrolling interests								0	(84,000,000)		(377,000,000)
Retained Earnings [Member] | IPALCO Enterprises, Inc. [Member]
Temporary Equity [Line Items]
Sale of subsidiary shares to noncontrolling interests						$ (84,000,000)	$ (377,000,000)		(84,000,000)	[2]	$ (377,000,000)	[2]
Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary Equity Reclassification								(4,000,000)					$ (19,000,000)
Redeemable Preferred Stock [Member] | DPL Subsidiary
Temporary Equity [Line Items]
Redeemable Noncontrolling Interest, Equity, Preferred, Redemption Value													$ 23,000,000
Acquire additional shares through 2016 [Member]
Temporary Equity [Line Items]
Investment Options, acquisition percentage					17.65%
Acquire additional shares through 2016 [Member] | IPALCO Enterprises, Inc. [Member]
Temporary Equity [Line Items]
Sale Agreement, Buyer Option To Purchase Ownership Interest, Sales Price					$ 349,000,000
Other Comprehensive Income (Loss) [Member]
Temporary Equity [Line Items]
Temporary Equity, Other Changes								$ (2,000,000)	$ 6,000,000

[1] Net income attributable to noncontrolling interest of $398 million and net loss attributable to redeemable stock of subsidiaries of $14 million for the year ended December 31, 2017. Net income attributable to noncontrolling interest of $364 million and net loss attributable to redeemable stock of subsidiaries of $11 million for the year ended December 31, 2016.

[2] See Note 17—Redeemable stock of subsidiaries for further information on increase in paid-in-capital transferred to redeemable stock of subsidiaries.