The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Property, Plant and Equipment, Net (Details) (USD $) In Millions, unless otherwise specified							6 Months Ended				6 Months Ended						6 Months Ended				6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Regulated assets [Member]	Dec. 31, 2012 Regulated assets [Member]	Jun. 30, 2013 Regulated assets [Member] Utility generation, distribution and transmission system [Member]	Dec. 31, 2012 Regulated assets [Member] Utility generation, distribution and transmission system [Member]	Jun. 30, 2013 Regulated assets [Member] Utility generation, distribution and transmission system [Member] Minimum [Member]	Jun. 30, 2013 Regulated assets [Member] Utility generation, distribution and transmission system [Member] Maximum [Member]	Jun. 30, 2013 Regulated assets [Member] Interstate pipeline assets [Member]	Dec. 31, 2012 Regulated assets [Member] Interstate pipeline assets [Member]	Jun. 30, 2013 Regulated assets [Member] Interstate pipeline assets [Member] Minimum [Member]	Jun. 30, 2013 Regulated assets [Member] Interstate pipeline assets [Member] Maximum [Member]	Jun. 30, 2013 Unregulated operation [Member]	Dec. 31, 2012 Unregulated operation [Member]	Jun. 30, 2013 Unregulated operation [Member] Independent power plants [Member]	Dec. 31, 2012 Unregulated operation [Member] Independent power plants [Member]	Jun. 30, 2013 Unregulated operation [Member] Independent power plants [Member] Minimum [Member]	Jun. 30, 2013 Unregulated operation [Member] Independent power plants [Member] Maximum [Member]	Jun. 30, 2013 Unregulated operation [Member] Other assets [Member]	Dec. 31, 2012 Unregulated operation [Member] Other assets [Member]	Jun. 30, 2013 Unregulated operation [Member] Other assets [Member] Minimum [Member]	Jun. 30, 2013 Unregulated operation [Member] Other assets [Member] Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment			$ 49,519	$ 49,036	$ 43,162	$ 42,682			$ 6,357	$ 6,354			$ 2,311	$ 1,860	$ 1,853	$ 1,428			$ 458	$ 432
Accumulated depreciation and amortization			(15,760)	(15,338)									(618)	(591)
Property, plant and equipment in service, net	35,452	34,967	33,759	33,698									1,693	1,269
Construction work-in-progress	2,819	2,647	1,900	1,900
Property, plant and equipment, net	$ 38,271	$ 37,614
Depreciable Life							5 years	80 years			3 years	80 years					5 years	30 years			3 years	30 years