Derivative Instruments and Hedging Activities (Details) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended																			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended																																													3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended				6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2011 USD ($)	Jun. 30, 2010 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2010 USD ($)	Dec. 31, 2010 USD ($)	Jun. 30, 2011 Interest Rate Derivatives Current Member Libor USD Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Current Member Euribor EUR Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Current Member Euribor EUR Member EUR (€)	Jun. 30, 2011 Interest Rate Derivatives Current Member Libor GBP Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Current Member Libor GBP Member GBP (£)	Jun. 30, 2011 Interest Rate Derivatives Current Member Securities Industry and Financial Markets Association Municipal Swap Index USD Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Libor USD Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Euribor EUR Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Euribor EUR Member EUR (€)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Libor GBP Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Libor GBP Member GBP (£)	Jun. 30, 2011 Interest Rate Derivatives Maximum Member Securities Industry and Financial Markets Association Municipal Swap Index USD Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Libor USD Member	Jun. 30, 2011 Interest Rate Derivatives Euribor EUR Member	Jun. 30, 2011 Interest Rate Derivatives Libor GBP Member	Jun. 30, 2011 Interest Rate Derivatives Securities Industry and Financial Markets Association Municipal Swap Index USD Member	Jun. 30, 2011 Interest Rate Derivatives USD ($)	Jun. 30, 2010 Interest Rate Derivatives USD ($)	Jun. 30, 2011 Interest Rate Derivatives USD ($)	Jun. 30, 2010 Interest Rate Derivatives USD ($)	Jun. 30, 2011 Interest Rate Derivatives Interest expense [Member] USD ($)	Jun. 30, 2010 Interest Rate Derivatives Interest expense [Member] USD ($)	Jun. 30, 2011 Interest Rate Derivatives Interest expense [Member] USD ($)	Jun. 30, 2010 Interest Rate Derivatives Interest expense [Member] USD ($)	Jun. 30, 2011 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Jun. 30, 2010 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Jun. 30, 2011 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Jun. 30, 2010 Interest Rate Derivatives Non-regulated cost of sales USD ($)	Jun. 30, 2011 Interest Rate Derivatives Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2010 Interest Rate Derivatives Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2011 Interest Rate Derivatives Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2010 Interest Rate Derivatives Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2011 Cross Currency Swaps Chilean Unidad De Fomento CLF Member USD ($)	Jun. 30, 2011 Cross Currency Swaps Chilean Unidad De Fomento CLF Member CLF	Jun. 30, 2011 Cross Currency Swaps USD ($)	Jun. 30, 2010 Cross Currency Swaps USD ($)	Jun. 30, 2011 Cross Currency Swaps USD ($)	Jun. 30, 2010 Cross Currency Swaps USD ($)	Jun. 30, 2011 Cross Currency Swaps Interest expense [Member] USD ($)	Jun. 30, 2010 Cross Currency Swaps Interest expense [Member] USD ($)	Jun. 30, 2011 Cross Currency Swaps Interest expense [Member] USD ($)	Jun. 30, 2010 Cross Currency Swaps Interest expense [Member] USD ($)	Jun. 30, 2011 Foreign Currency Options Member Euro EUR Member USD ($)	Jun. 30, 2011 Foreign Currency Options Member Euro EUR Member EUR (€)	Jun. 30, 2011 Foreign Currency Options Member Brazilian Real BRL Member USD ($)	Jun. 30, 2011 Foreign Currency Options Member Brazilian Real BRL Member BRL	Jun. 30, 2011 Foreign Currency Forwards Member Philippine Peso PHP Member USD ($)	Jun. 30, 2011 Foreign Currency Forwards Member Philippine Peso PHP Member PHP	Jun. 30, 2011 Foreign Currency Forwards Member British Pound GBP Member USD ($)	Jun. 30, 2011 Foreign Currency Forwards Member British Pound GBP Member GBP (£)	Jun. 30, 2011 Foreign Currency Forwards Member Chilean Peso CLP Member USD ($)	Jun. 30, 2011 Foreign Currency Forwards Member Chilean Peso CLP Member CLP	Jun. 30, 2011 Foreign Currency Forwards Member Colombian Peso COP Member USD ($)	Jun. 30, 2011 Foreign Currency Forwards Member Colombian Peso COP Member COP	Jun. 30, 2011 Foreign Currency Forwards Member Argentine Peso ARS Member USD ($)	Jun. 30, 2011 Foreign Currency Forwards Member Argentine Peso ARS Member ARS	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Euro EUR Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Euro EUR Member EUR (€)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Brazilian Real BRL Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Brazilian Real BRL Member BRL	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Philippine Peso PHP Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Philippine Peso PHP Member PHP	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Argentine Peso ARS Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Argentine Peso ARS Member ARS	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Kazakhstani Tenge KZT Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Kazakhstani Tenge KZT Member KZT	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Hungarian Forint HUF Member USD ($)	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Hungarian Forint HUF Member HUF	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Cameroon Franc XAF Member XAF	Jun. 30, 2011 Embedded Foreign Currency Derivatives Member Cameroon Franc XAF Member USD ($)	Jun. 30, 2011 Commodity Natural Gas MMBTU Member MMBTU	Jun. 30, 2011 Commodity Petcoke Metric Tons Member MetricTons	Jun. 30, 2011 Commodity Aluminum M Wh Member MWh	Jun. 30, 2011 Commodity USD ($)	Jun. 30, 2011 Gas Andes [Member]	Jun. 30, 2011 Quoted Market Prices in Active Market for Identical Assets (Level 1) USD ($)	Dec. 31, 2010 Quoted Market Prices in Active Market for Identical Assets (Level 1) USD ($)	Jun. 30, 2011 Significant Other Observable Inputs (Level 2) USD ($)	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) USD ($)	Jun. 30, 2011 Significant Unobservable Inputs (Level 3) USD ($)	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) USD ($)	Jun. 30, 2011 Derivative Instruments Hedging Member USD ($)	Dec. 31, 2010 Derivative Instruments Hedging Member USD ($)	Jun. 30, 2011 Derivative Instruments Not Hedging Member USD ($)	Dec. 31, 2010 Derivative Instruments Not Hedging Member USD ($)	Jun. 30, 2011 Foreign Currency USD ($)	Jun. 30, 2010 Foreign Currency USD ($)	Jun. 30, 2011 Foreign Currency USD ($)	Jun. 30, 2010 Foreign Currency USD ($)	Jun. 30, 2011 Foreign Currency Foreign currency transaction gains (losses) USD ($)	Jun. 30, 2010 Foreign Currency Foreign currency transaction gains (losses) USD ($)	Jun. 30, 2011 Foreign Currency Foreign currency transaction gains (losses) USD ($)	Jun. 30, 2010 Foreign Currency Foreign currency transaction gains (losses) USD ($)	Jun. 30, 2011 Foreign Currency Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2010 Foreign Currency Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2011 Foreign Currency Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2010 Foreign Currency Net Equity In Earnings Of Affiliates Member USD ($)	Jun. 30, 2011 Commodity & Other USD ($)	Jun. 30, 2010 Commodity & Other USD ($)	Jun. 30, 2011 Commodity & Other Non-regulated revenue USD ($)	Jun. 30, 2010 Commodity & Other Non-regulated revenue USD ($)	Jun. 30, 2011 Commodity & Other Non-regulated revenue USD ($)	Jun. 30, 2010 Commodity & Other Non-regulated revenue USD ($)	Jun. 30, 2011 Commodity & Other Non-regulated cost of sales USD ($)	Jun. 30, 2010 Commodity & Other Non-regulated cost of sales USD ($)	Jun. 30, 2011 Commodity & Other Non-regulated cost of sales USD ($)	Jun. 30, 2010 Commodity & Other Non-regulated cost of sales USD ($)	Jun. 30, 2011 Discontinued Operations Member USD ($)	Jun. 30, 2010 Discontinued Operations Member USD ($)
Derivative Tables [Line Items]
Notional Amount Of Interest Rate Derivatives						$ 3,282	$ 1,558	€ 1,074	$ 45	£ 28	$ 40	$ 3,609	$ 1,558	€ 1,074	$ 68	£ 42	$ 40
Weighted Average Remaining Term																		9	13	17	12																	15	15									<1	<1	<1	<1	<1	<1	1	1	<1	<1	<1	<1	1	1	2	2	1	1	3	3	11	11	9	9	1	1	2	2	11	13	9
% of Debt Currently Hedged by Index																		72.00%	65.00%	47.00%																		82.00%	82.00%
Notional Amount Of Foreign Currency Derivatives																																						262										57	40	164	268	4	170	31	18	181	87,779	75	137,110	20	90	32	22	5	8	416	18,048	193	795	215	31,358	97	17,819	352	1
Notional (CLF)																																							6
Probability Adjusted Notional																																																27		52
Notional																																																																												34,000,000	13,000,000	17,000,000
Ownership interest in two gas transportation companies																																																																																13.00%
Current assets:
Foreign currency derivatives	18		18		7																																																																												0	0	14	4	4	3	1	0	17	7
Interest rate derivatives	6		6		0																																																																												0	0	6	0	0	0	6	0	0	0
Commodity and other derivatives
Commodity and other derivatives	13		13		5																																																																												0	0	4	2	9	3	0	0	13	5
Total current assets	37		37		12																																																																												0	0	24	6	13	6	7	0	30	12
Noncurrent assets:
Interest rate derivatives	37		37		49																																																																												0	0	37	49	0	0	37	49	0	0
Foreign currency derivatives	46		46		31																																																																												0	0	5	4	41	27	0	0	46	31
Cross currency derivatives	20		20		12																																																																												0	0	0	0	20	12	20	12	0	0
Commodity and other derivatives	15		15		20																																																																												0	0	6	4	9	16	0	0	15	20
Total noncurrent assets	118		118		112																																																																												0	0	48	57	70	55	57	61	61	51
Total assets	155		155		124																																																																												0	0	72	63	83	61	64	61	91	63
Current liabilities:
Interest rate derivatives	148		148		137																																																																												0	0	135	137	13	0	141	126	7	11
Cross currency derivatives	5		5		2																																																																												0	0	0	0	5	2	5	2	0	0
Foreign currency derivatives	12		12		13																																																																												0	0	11	13	1	0	7	8	5	5
Commodity and other derivatives
Commodity and other derivatives	4		4		0																																																																												0	0	4	0	0	0	0	0	4	0
Total current liabilities	169		169		152																																																																												0	0	150	150	19	2	153	136	16	16
Noncurrent liabilities:
Interest rate derivatives	250		250		247																																																																												0	0	203	246	47	1	236	232	14	15
Cross currency derivatives																																																																																							0	0	0	0
Foreign currency derivatives	18		18		23																																																																												0	0	12	15	6	8	0	0	18	23
Commodity and other derivatives
Commodity and other derivatives	3		3		1																																																																												0	0	2	0	1	1	0	0	3	1
Total noncurrent liabilities	271		271		271																																																																												0	0	217	261	54	10	236	232	35	39
Total liabilities	440		440		423																																																																												0	0	367	411	73	12	389	368	51	55
AOCI to be recognized in next 12 months table
Accumulated Other Comprehensive Income (Loss)																						(108)		(108)																(4)		(4)																																					(1)												(7)		(7)
Gain Loss By Type Of Derivative Tables
Gains (Losses) Recognized in AOCL	(141)	(199)	(91)	(272)																		(144)	(168)	(92)	(250)															11	(26)	3	(29)																																																(7)	7	(2)	7									(1)	(12)
Gains (Losses) Reclassified from AOCL into Earnings	(24)	(31)	(59)	(61)																						(27)	(29)	(53)	(57)	(1)	0	(2)	0	(1)	(1)	(2)	(2)							7	(1)	2	(2)																																																(2)	0	(4)	0							0	0
Gains (Losses) Due to Discontinued Operations Excluded From Amount Reclassified from AOCL into Earnings	0	(8)																																																																																																															0	(10)
Gains (Losses) Recognized in Earnings (ineffective portion)	(3)	(2)	(10)	(5)																						0	0	(7)	(8)					(1)	(1)	(1)	(1)							(2)	(1)	(2)	4																																																0	0	0	0
Gains (Losses) Recognized in Earnings (not designated as hedging instruments)	4	(22)	16	(19)																						(1)	(1)	(1)	(5)																																																																		20	(27)	27	(25)	0	1	0	2			(13)	4	(9)	4	(2)	1	(1)	5
IPL Regulatory Activity Narrative
Change In Regulatory Asset Resulting From Change In Derivative Fair Value	2	2	2	1
Change In Regulatory Liability Resulting From Change In Derivative Fair Value	$ 7	$ 5	$ 6	$ 6