Derivative Instruments and Hedging Activities - Part 1 (Details) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)	Dec. 31, 2011 USD ($)	Jun. 30, 2012 Gener Subsidiary [Member] USD ($)	Dec. 31, 2011 Gener Subsidiary [Member] USD ($)	Jun. 30, 2012 DPL Subsidiary [Member] USD ($)	Dec. 31, 2011 DPL Subsidiary [Member] USD ($)	Jun. 30, 2012 Designated as Hedging Instruments USD ($)	Dec. 31, 2011 Designated as Hedging Instruments USD ($)	Jun. 30, 2012 Not Designated as Hedging Instruments USD ($)	Dec. 31, 2011 Not Designated as Hedging Instruments USD ($)	Jun. 30, 2012 Level 1 USD ($)	Dec. 31, 2011 Level 1 USD ($)	Jun. 30, 2012 Level 2 USD ($)	Dec. 31, 2011 Level 2 USD ($)	Jun. 30, 2012 Level 3 USD ($)	Dec. 31, 2011 Level 3 USD ($)	Jun. 30, 2012 Interest Rate Derivatives Libor USD [Member]	Jun. 30, 2012 Interest Rate Derivatives Euribor EUR [Member]	Jun. 30, 2012 Interest Rate Derivatives Libor GBP [Member]	Jun. 30, 2012 Interest Rate Derivatives Current [Member] Libor USD [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] EUR (€)	Jun. 30, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] GBP (£)	Jun. 30, 2012 Interest Rate Derivatives Maximum [Member] Libor USD [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Maximum [Member] Euribor EUR [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Maximum [Member] Euribor EUR [Member] EUR (€)	Jun. 30, 2012 Interest Rate Derivatives Maximum [Member] Libor GBP [Member] USD ($)	Jun. 30, 2012 Interest Rate Derivatives Maximum [Member] Libor GBP [Member] GBP (£)	Jun. 30, 2012 Cross Currency Swaps Chilean Unidad De Fomento CLF [Member] USD ($)	Jun. 30, 2012 Cross Currency Swaps Chilean Unidad De Fomento CLF [Member] CLF	Jun. 30, 2012 Foreign Currency Options Euro EUR [Member] USD ($)	Jun. 30, 2012 Foreign Currency Options Euro EUR [Member] EUR (€)	Jun. 30, 2012 Foreign Currency Options Philippine Peso PHP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Options Philippine Peso PHP [Member] PHP	Jun. 30, 2012 Foreign Currency Options British Pound GBP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Options British Pound GBP [Member] GBP (£)	Jun. 30, 2012 Foreign Currency Forwards Euro EUR [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards Euro EUR [Member] EUR (€)	Jun. 30, 2012 Foreign Currency Forwards Philippine Peso PHP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards Philippine Peso PHP [Member] PHP	Jun. 30, 2012 Foreign Currency Forwards British Pound GBP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards British Pound GBP [Member] GBP (£)	Jun. 30, 2012 Foreign Currency Forwards Chilean Peso CLP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards Chilean Peso CLP [Member] CLP	Jun. 30, 2012 Foreign Currency Forwards Colombian Peso COP [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards Colombian Peso COP [Member] COP	Jun. 30, 2012 Foreign Currency Forwards Argentine Peso ARS [Member] USD ($)	Jun. 30, 2012 Foreign Currency Forwards Argentine Peso ARS [Member] ARS	Jun. 30, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] USD ($)	Jun. 30, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] EUR (€)	Jun. 30, 2012 Embedded Foreign Currency Derivatives Philippine Peso PHP [Member] USD ($)	Jun. 30, 2012 Embedded Foreign Currency Derivatives Philippine Peso PHP [Member] PHP	Jun. 30, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] USD ($)	Jun. 30, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] ARS	Jun. 30, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] USD ($)	Jun. 30, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] KZT	Jun. 30, 2012 Commodity Derivatives Natural Gas MMBTU [Member] MMBTU	Jun. 30, 2012 Commodity Derivatives Petcoke Metric Tons [Member] MetricTons	Jun. 30, 2012 Commodity Derivatives Aluminum M Wh [Member] MWh	Jun. 30, 2012 Commodity Derivatives Heating Oil Gallons [Member] gallon	Jun. 30, 2012 Commodity Derivatives Coal Metric Tons [Member] MetricTons	Jun. 30, 2012 Commodity Derivatives Power MWh [Member] MWh
Derivative Tables [Line Items]
Notional Amount Of Interest Rate Derivatives																							$ 3,604	$ 793	€ 626	$ 94	£ 60	$ 4,608	$ 796	€ 629	$ 158	£ 101
Weighted Average Remaining Term																				10	10	14											14	14	<1	<1	<1	<1	<1	<1	2	2	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	9	9	11	11	12	12	4	4	11	12	8	<1	1	3
% of Debt Currently Hedged by Index																				69.00%	63.00%	91.00%											85.00%	85.00%
Notional Amount Of Foreign Currency Derivatives																																	253		87	68	38	1,625	3	2	131	95	51	2,183	37	24	122	60,833	105	189,847	7	31	3	2	1,553	64,870	208	943	9	1,275
Notional (CLF)																																		6
Probability Adjusted Notional																																			56		15		2
Notional																																																													30,000,000	12,000,000	15,000,000	1,000,000	2,000,000	3,000,000
Current assets:
Foreign currency derivatives	14		14		28					6	10	8	18	0	0	9	24	5	4
Commodity and other derivatives	27		27		21					2	2	25	19	0	2	19	16	8	3
Total current assets	41		41		49					8	12	33	37	0	2	28	40	13	7
Noncurrent assets:
Interest rate derivatives	2		2		0					0	0	2	0	0	0	2	0	0	0
Foreign currency derivatives	56		56		61					6	3	50	58	0	0	6	3	50	58
Cross currency derivatives	4		4		1					4	1	0	0	0	0	4	0	0	1
Commodity and other derivatives	13		13		9					1	0	12	9	0	0	5	9	8	0
Total noncurrent assets	75		75		71					11	4	64	67	0	0	17	12	58	59
Total assets	116		116		120					19	16	97	104	0	2	45	52	71	66
Current liabilities:
Interest rate derivatives	122		122		119					114	110	8	9	0	0	78	97	44	22
Cross currency derivatives	6		6		5					6	5	0	0	0	0	6	0	0	5
Foreign currency derivatives	5		5		6					3	1	2	5	0	0	4	5	1	1
Commodity and other derivatives	27		27		23					3	0	24	23	0	0	20	17	7	6
Total current liabilities	160		160		153					126	116	34	37	0	0	108	119	52	34
Noncurrent liabilities:
Interest rate derivatives	487		487		440					473	425	14	15	0	0	250	334	237	106
Cross currency derivatives	4		4		14					4	14	0	0	0	0	4	0	0	14
Foreign currency derivatives	83		83		20					0	0	83	20	0	0	76	10	7	10
Commodity and other derivatives	71		71		63					4	3	67	60	0	0	10	13	61	50
Total noncurrent derivative liabilities	645		645		537					481	442	164	95	0	0	340	357	305	180
Total liabilities	805		805		690					607	558	198	132	0	0	448	476	357	214
IPL Regulatory Activity Narrative
(Increase) decrease in regulatory assets	(8)	(2)	(5)	(2)
Increase (decrease) in regulatory liabilities	(1)	7	(1)	6
Credit Risk-Related Contingent Features [Line Items]
Net liability position, derivative transactions						10	18	29
Collateral posted for cross currency swap derivative transactions	20		20		16			20	16
Cash Collateral Received From Counterparties	$ 0		$ 0		$ 3			$ 0	$ 3