Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Accounting Policies [Abstract]

Inventory Components

Inventory consisted of the following:

	December 31,
(in millions)	2011		2010
Coal, gas, fuel oil and other raw materials	$	211	$	184
Spare parts, materials and supplies	413		384
Total inventory	$	624	$	568

Schedule of Purchased Emission Allowances, Exemptions and Offsets

The following table summarizes the amount of current and noncurrent purchased emission allowances, exemptions and offsets and the line item on the consolidated balance sheets.

	December 31,
(in millions)	2011		2010
Purchased emission allowances
Current (included in other current assets)	$	20	$	29
Noncurrent(included in other long-term assets)	92		31

Estimated Useful Lives and Weighted-Average Useful lives of Utility Property, Plant and Equipment

Estimated useful lives (authorized by the CPUC) and weighted-average useful lives of SCE's property, plant and equipment, are as follows:

	Estimated Useful Lives	Weighted-Average Useful Lives
Generation plant	25 years to 70 years	40 years
Distribution plant	30 years to 60 years	40 years
Transmission plant	35 years to 65 years	46 years
General and Other plant	5 years to 60 years	22 years

Useful Lives for Property, Plant and Equipment

Estimated useful lives for property, plant and equipment are as follows:

Power plant facilities	3 to 35 years
Leasehold improvements	Shorter of life of lease or estimated useful life
Emission allowances	25 to 33.75 years
Equipment, furniture and fixtures	3 to 10 years

Reconciliation of the Changes in ARO Liability

A reconciliation of the changes in the ARO liability is as follows:

(in millions)	2011			2010
Beginning balance	$	2,561		$	3,241
Accretion expense	68			198
Revisions1	41			(867		)
Liabilities added	19			9
Liabilities settled	(1		)	(1		)
Transfers in or out2	—			(19		)
Ending balance	$	2,688		$	2,561

¹  Revisions in 2010 represent the most recent site-specific studies approved by the CPUC.

²  Transfers in or out consist of the deconsolidation of the Big 4 projects (Kern River, Midway-Sunset, Sycamore and Watson) effective January 1, 2010. For further discussion, see Note 3.

EPS Computation

EPS attributable to Edison International common shareholders was computed as follows:

	Years ended December 31,
(in millions)	2011				2010				2009
Basic earnings per share – continuing operations:
Income from continuing operations attributable to common shareholders, net of tax	$	(34	)		$	1,252			$	856
Participating securities dividends	—				(5		)		(6		)
Income from continuing operations available to common shareholders	$	(34	)		$	1,247			$	850
Weighted average common shares outstanding	326				326				326
Basic earnings per share – continuing operations	$	(0.10	)		$	3.83			$	2.61
Diluted earnings per share – continuing operations:
Income from continuing operations available to common shareholders	$	(34	)		$	1,247			$	850
Income impact of assumed conversions	—			1	5				1
Income from continuing operations available to common shareholders and assumed conversions	$	(34	)		$	1,252			$	851
Weighted average common shares outstanding	326				326				326
Incremental shares from assumed conversions	—			1	3			2	1			2
Adjusted weighted average shares – diluted	326				329				327
Diluted earnings per share – continuing operations	$	(0.10	)		$	3.81			$	2.60

¹  Due to a loss for the period, there are no incremental shares in the computation because such shares would be considered antidilutive.

²  Stock-based compensation awards to purchase 5,981,090, and 8,547,090 shares of common stock for the years ended December 31, 2010 and 2009, respectively, were outstanding, but were not included in the computation of diluted earnings per share because the exercise price of the awards was greater than the average market price of the common shares during the respective periods and, therefore, the effect would have been antidilutive.