Derivative Instruments and Hedging Activities (Details) In Millions, unless otherwise specified	3 Months Ended							3 Months Ended
	Mar. 31, 2012 USD ($)	Mar. 31, 2011 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2012 Gener Subsidiary [Member] USD ($)	Dec. 31, 2011 Gener Subsidiary [Member] USD ($)	Mar. 31, 2012 DPL Subsidiary [Member] USD ($)	Dec. 31, 2011 DPL Subsidiary [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives USD ($)	Mar. 31, 2011 Interest Rate Derivatives USD ($)	Mar. 31, 2012 Interest Rate Derivatives Interest expense USD ($)	Mar. 31, 2011 Interest Rate Derivatives Interest expense USD ($)	Mar. 31, 2012 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Mar. 31, 2011 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Mar. 31, 2012 Interest Rate Derivatives Net equity in earnings of affiliates USD ($)	Mar. 31, 2011 Interest Rate Derivatives Net equity in earnings of affiliates USD ($)	Mar. 31, 2012 Interest Rate Derivatives Gain on sale of investments [Member] USD ($)	Mar. 31, 2011 Interest Rate Derivatives Gain on sale of investments [Member] USD ($)	Mar. 31, 2012 Cross Currency Swaps USD ($)	Mar. 31, 2011 Cross Currency Swaps USD ($)	Mar. 31, 2012 Cross Currency Swaps Interest expense USD ($)	Mar. 31, 2011 Cross Currency Swaps Interest expense USD ($)	Mar. 31, 2012 Cross Currency Swaps Foreign currency transaction gains (losses) [Member] USD ($)	Mar. 31, 2011 Cross Currency Swaps Foreign currency transaction gains (losses) [Member] USD ($)	Mar. 31, 2012 Foreign Currency USD ($)	Mar. 31, 2011 Foreign Currency USD ($)	Mar. 31, 2012 Foreign Currency Foreign currency transaction gains (losses) [Member] USD ($)	Mar. 31, 2011 Foreign Currency Foreign currency transaction gains (losses) [Member] USD ($)	Mar. 31, 2012 Commodity & Other USD ($)	Mar. 31, 2011 Commodity & Other USD ($)	Mar. 31, 2012 Commodity & Other Non-regulated revenue USD ($)	Mar. 31, 2011 Commodity & Other Non-regulated revenue USD ($)	Mar. 31, 2012 Commodity & Other Non-regulated cost of sales USD ($)	Mar. 31, 2011 Commodity & Other Non-regulated cost of sales USD ($)	Mar. 31, 2012 Commodity & Other Regulated revenue USD ($)	Mar. 31, 2011 Commodity & Other Regulated revenue USD ($)	Mar. 31, 2012 Commodity & Other Regulated cost of sales USD ($)	Mar. 31, 2011 Commodity & Other Regulated cost of sales USD ($)	Mar. 31, 2012 Designated as Hedging Instruments USD ($)	Dec. 31, 2011 Designated as Hedging Instruments USD ($)	Mar. 31, 2012 Not Designated as Hedging Instruments USD ($)	Dec. 31, 2011 Not Designated as Hedging Instruments USD ($)	Mar. 31, 2012 Level 1 USD ($)	Dec. 31, 2011 Level 1 USD ($)	Mar. 31, 2012 Level 2 USD ($)	Dec. 31, 2011 Level 2 USD ($)	Mar. 31, 2012 Level 3 USD ($)	Dec. 31, 2011 Level 3 USD ($)	Mar. 31, 2012 Interest Rate Derivatives Libor USD [Member]	Mar. 31, 2012 Interest Rate Derivatives Euribor EUR [Member]	Mar. 31, 2012 Interest Rate Derivatives Libor GBP [Member]	Mar. 31, 2012 Interest Rate Derivatives Current [Member] Libor USD [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] EUR (€)	Mar. 31, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] GBP (£)	Mar. 31, 2012 Interest Rate Derivatives Maximum [Member] Libor USD [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Maximum [Member] Euribor EUR [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Maximum [Member] Euribor EUR [Member] EUR (€)	Mar. 31, 2012 Interest Rate Derivatives Maximum [Member] Libor GBP [Member] USD ($)	Mar. 31, 2012 Interest Rate Derivatives Maximum [Member] Libor GBP [Member] GBP (£)	Mar. 31, 2012 Cross Currency Swaps Chilean Unidad De Fomento CLF [Member] USD ($)	Mar. 31, 2012 Cross Currency Swaps Chilean Unidad De Fomento CLF [Member] CLF	Mar. 31, 2012 Foreign Currency Options Euro EUR [Member] USD ($)	Mar. 31, 2012 Foreign Currency Options Euro EUR [Member] EUR (€)	Mar. 31, 2012 Foreign Currency Options Brazilian Real BRL [Member] USD ($)	Mar. 31, 2012 Foreign Currency Options Brazilian Real BRL [Member] BRL	Mar. 31, 2012 Foreign Currency Options Philippine Peso PHP [Member] USD ($)	Mar. 31, 2012 Foreign Currency Options Philippine Peso PHP [Member] PHP	Mar. 31, 2012 Foreign Currency Options British Pound GBP [Member] USD ($)	Mar. 31, 2012 Foreign Currency Options British Pound GBP [Member] GBP (£)	Mar. 31, 2012 Foreign Currency Options Argentine Peso ARS [Member] USD ($)	Mar. 31, 2012 Foreign Currency Options Argentine Peso ARS [Member] ARS	Mar. 31, 2012 Foreign Currency Forwards Euro EUR [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards Euro EUR [Member] EUR (€)	Mar. 31, 2012 Foreign Currency Forwards British Pound GBP [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards British Pound GBP [Member] GBP (£)	Mar. 31, 2012 Foreign Currency Forwards Chilean Peso CLP [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards Chilean Peso CLP [Member] CLP	Mar. 31, 2012 Foreign Currency Forwards Colombian Peso COP [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards Colombian Peso COP [Member] COP	Mar. 31, 2012 Foreign Currency Forwards Argentine Peso ARS [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards Argentine Peso ARS [Member] ARS	Mar. 31, 2012 Foreign Currency Forwards Hungarian Forint HUF [Member] USD ($)	Mar. 31, 2012 Foreign Currency Forwards Hungarian Forint HUF [Member] HUF	Mar. 31, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] USD ($)	Mar. 31, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] EUR (€)	Mar. 31, 2012 Embedded Foreign Currency Derivatives Philippine Peso PHP [Member] USD ($)	Mar. 31, 2012 Embedded Foreign Currency Derivatives Philippine Peso PHP [Member] PHP	Mar. 31, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] USD ($)	Mar. 31, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] ARS	Mar. 31, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] USD ($)	Mar. 31, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] KZT	Mar. 31, 2012 Commodity Derivatives Natural Gas MMBTU [Member] MMBTU	Mar. 31, 2012 Commodity Derivatives Petcoke Metric Tons [Member] MetricTons	Mar. 31, 2012 Commodity Derivatives Aluminum M Wh [Member] MWh	Mar. 31, 2012 Commodity Derivatives Heating Oil Gallons [Member] gallon	Mar. 31, 2012 Commodity Derivatives Coal Metric Tons [Member] MetricTons
Derivative Tables [Line Items]
Notional Amount Of Interest Rate Derivatives																																																			$ 3,657	$ 891	€ 668	$ 107	£ 67	$ 4,668	$ 891	€ 668	$ 132	£ 83
Weighted Average Remaining Term																																																10	10	13											14	14	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	2	2	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	9	9	11	11	11	11	9	9	11	12	8	<1	1
% of Debt Currently Hedged by Index																																																71.00%	65.00%	92.00%											85.00%	85.00%
Notional Amount Of Foreign Currency Derivatives																																																													253		83	62	63	110	30	1,285	2	1	4	18	133	95	29	18	169	84,974	77	137,722	7	31	1	402	3	2	1,247	53,591	215	943	196	29,023
Notional (CLF)																																																														6
Probability Adjusted Notional																																																															44		53		18		2		0
Notional																																																																																													31,000,000	12,000,000	15,000,000	2,000,000	3,000,000
Current assets:
Foreign currency derivatives	15		28																																			5	10	10	18	0	0	11	24	4	4
Commodity and other derivatives	20		21																																			1	2	19	19	2	2	16	16	2	3
Total current assets	35		49																																			6	12	29	37	2	2	27	40	6	7
Noncurrent assets:
Foreign currency derivatives	55		61																																			4	3	51	58	0	0	4	3	51	58
Cross currency derivatives	5		1																																			5	1	0	0	0	0	5	0	0	1
Commodity and other derivatives	14		9																																			0	0	14	9	0	0	5	9	9	0
Total noncurrent assets	74		71																																			9	4	65	67	0	0	14	12	60	59
Total assets	109		120																																			15	16	94	104	2	2	41	52	66	66
Current liabilities:
Interest rate derivatives	113		119																																			105	110	8	9	0	0	96	97	17	22
Cross currency derivatives	4		5																																			4	5	0	0	0	0	4	0	0	5
Foreign currency derivatives	9		6																																			5	1	4	5	0	0	8	5	1	1
Commodity and other derivatives	31		23																																			1	0	30	23	0	0	27	17	4	6
Total current liabilities	157		153																																			115	116	42	37	0	0	135	119	22	34
Noncurrent liabilities:
Interest rate derivatives	391		440																																			376	425	15	15	0	0	284	334	107	106
Cross currency derivatives	1		14																																			1	14	0	0	0	0	1	0	0	14
Foreign currency derivatives	34		20																																			0	0	34	20	0	0	27	10	7	10
Commodity and other derivatives	65		63																																			5	3	60	60	0	0	13	13	52	50
Total noncurrent derivative liabilities	491		537																																			382	442	109	95	0	0	325	357	166	180
Total liabilities	648		690																																			497	558	151	132	0	0	460	476	188	214
AOCI to be recognized in next 12 months table
Accumulated Other Comprehensive Income (Loss)								(99)										9						(2)				(1)
Gain Loss By Type Of Derivative Tables
Gains (Losses) Recognized in AOCL	25	50						11	52									14	(8)					6	5			(6)	1
Gains (Losses) Reclassified from AOCL into Earnings	(114)	(40)								(32)	(26)	(2)	(1)	(1)	(1)	(92)	0			(3)	(5)	18	(5)			0	(2)			(2)	0
Gains (Losses) Recognized in Earnings (ineffective portion)	(1)	(7)								(1)	(7)			0	0					0	0					0	0
Gains (Losses) Recognized in Earnings (not designated as hedging instruments)	(31)	12								(2)	0															(38)	7			14	4	3	1	(4)	0	(4)	0
IPL Regulatory Activity Narrative
(Increase) decrease in regulatory assets	3	0
Increase (decrease) in regulatory liabilities	0	(1)
Credit Risk-Related Contingent Features [Line Items]
Net liability position, derivative transactions				5	18	38
Collateral posted for cross currency swap derivative transactions	26		16			26	16
Cash Collateral Received From Counterparties	$ 2		$ 3			$ 2	$ 3