Commitments And Contingencies (Operating Expense Purchase Obligations) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) MW
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 2,292
Individual commitments incurred	1
Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1,584	[1]
DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1,419	[1],[2]
Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	165	[1]
Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	398
Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	267	[3]
SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	22
Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	21	[4]
2016 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	524
2016 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	202	[1]
2016 [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	125	[1],[2]
2016 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	77	[1]
2016 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	173
2016 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	129	[3]
2016 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	14
2016 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	6	[4]
2017 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	350
2017 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	182	[1]
2017 [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	138	[1],[2]
2017 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	44	[1]
2017 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	82
2017 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	76	[3]
2017 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	8
2017 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
2018 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	279
2018 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	175	[1]
2018 [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	131	[1],[2]
2018 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	44	[1]
2018 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	52
2018 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	50	[3]
2018 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
2018 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
2019 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	200
2019 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	143	[1]
2019 [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	143	[1],[2]
2019 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
2019 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	43
2019 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	12	[3]
2019 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
2019 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
2020 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	167
2020 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	133	[1]
2020 [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	133	[1],[2]
2020 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
2020 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	32
2020 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
2020 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
2020 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
Thereafter [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	772
Thereafter [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	749	[1]
Thereafter [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	749	[1],[2]
Thereafter [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
Thereafter [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	16
Thereafter [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
Thereafter [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
Thereafter [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	7	[4]
IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1,792
IPL [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 1,420	[1]
IPL [Member] | DAEC IPL [Member]
Long-term Purchase Commitment [Line Items]
Approved amount of electric power capacity (in megawatts) | MW	431
IPL [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 1,419	[1],[2]
IPL [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1	[1]
IPL [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	228
IPL [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	121	[3]
IPL [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	22
IPL [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1	[4]
IPL [Member] | 2016 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	306
IPL [Member] | 2016 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	126	[1]
IPL [Member] | 2016 [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	125	[1],[2]
IPL [Member] | 2016 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1	[1]
IPL [Member] | 2016 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	95
IPL [Member] | 2016 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	70	[3]
IPL [Member] | 2016 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	14
IPL [Member] | 2016 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	1	[4]
IPL [Member] | 2017 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	218
IPL [Member] | 2017 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	138	[1]
IPL [Member] | 2017 [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	138	[1],[2]
IPL [Member] | 2017 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
IPL [Member] | 2017 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	42
IPL [Member] | 2017 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	30	[3]
IPL [Member] | 2017 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	8
IPL [Member] | 2017 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
IPL [Member] | 2018 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	183
IPL [Member] | 2018 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	131	[1]
IPL [Member] | 2018 [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	131	[1],[2]
IPL [Member] | 2018 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
IPL [Member] | 2018 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	35
IPL [Member] | 2018 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	17	[3]
IPL [Member] | 2018 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
IPL [Member] | 2018 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
IPL [Member] | 2019 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	175
IPL [Member] | 2019 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	143	[1]
IPL [Member] | 2019 [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	143	[1],[2]
IPL [Member] | 2019 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
IPL [Member] | 2019 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	28
IPL [Member] | 2019 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	4	[3]
IPL [Member] | 2019 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
IPL [Member] | 2019 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
IPL [Member] | 2020 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	151
IPL [Member] | 2020 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	133	[1]
IPL [Member] | 2020 [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	133	[1],[2]
IPL [Member] | 2020 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
IPL [Member] | 2020 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	18
IPL [Member] | 2020 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
IPL [Member] | 2020 [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
IPL [Member] | 2020 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
IPL [Member] | Thereafter [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	759
IPL [Member] | Thereafter [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	749	[1]
IPL [Member] | Thereafter [Member] | DAEC [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	749	[1],[2]
IPL [Member] | Thereafter [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
IPL [Member] | Thereafter [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	10
IPL [Member] | Thereafter [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
IPL [Member] | Thereafter [Member] | SO2 emission allowances [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0
IPL [Member] | Thereafter [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
WPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	482
WPL [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	164	[1]
WPL [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	170
WPL [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	146	[3]
WPL [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
WPL [Member] | 2016 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	215
WPL [Member] | 2016 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	76	[1]
WPL [Member] | 2016 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	78
WPL [Member] | 2016 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	59	[3]
WPL [Member] | 2016 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	2	[4]
WPL [Member] | 2017 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	130
WPL [Member] | 2017 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	44	[1]
WPL [Member] | 2017 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	40
WPL [Member] | 2017 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	46	[3]
WPL [Member] | 2017 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
WPL [Member] | 2018 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	94
WPL [Member] | 2018 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	44	[1]
WPL [Member] | 2018 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	17
WPL [Member] | 2018 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	33	[3]
WPL [Member] | 2018 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
WPL [Member] | 2019 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	23
WPL [Member] | 2019 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
WPL [Member] | 2019 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	15
WPL [Member] | 2019 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	8	[3]
WPL [Member] | 2019 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
WPL [Member] | 2020 [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	14
WPL [Member] | 2020 [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
WPL [Member] | 2020 [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	14
WPL [Member] | 2020 [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
WPL [Member] | 2020 [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[4]
WPL [Member] | Thereafter [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	6
WPL [Member] | Thereafter [Member] | Purchased Power [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[1]
WPL [Member] | Thereafter [Member] | Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	6
WPL [Member] | Thereafter [Member] | Coal [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	0	[3]
WPL [Member] | Thereafter [Member] | Other [Member]
Long-term Purchase Commitment [Line Items]
Minimum future commitments	$ 0	[4]

[1] Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.

[2] Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.

[3] Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2015 regarding expected future usage, which is subject to change.

[4] Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.