Other Investments (Tables)

9 Months Ended

Sep. 30, 2013

Regulated Entity, Other Assets, Noncurrent [Abstract]

Amortized Cost and Fair Value of the Trust Investments

The following table sets forth amortized cost and fair value of the trust investments:

	Longest Maturity Dates	Amortized Cost						Fair Value
(in millions)		September 30, 2013			December 31, 2012			September 30, 2013			December 31, 2012
Stocks	—	$	635		$	978		$	2,027		$	2,271
Municipal bonds	2051	701			518			796			644
U.S. government and agency securities	2043	861			547			924			603
Corporate bonds	2054	176			324			221			410
Short-term investments, primarily cash equivalents	One-year	351			117			367			121
Total investments		2,724			2,484			4,335			4,049
Net payables		(3		)	(1		)	(3		)	(1		)
Total nuclear decommissioning trusts		$	2,721		$	2,483		$	4,332		$	4,048

Summary of Changes in the Fair Value of Trust

The following table sets forth a summary of changes in the fair value of the trust:

	Three months ended September 30,						Nine months ended September 30,
(in millions)	2013			2012			2013			2012
Balance at beginning of period	$	4,182		$	3,810		$	4,048		$	3,592
Gross realized gains	119			13			261			54
Gross realized losses	(17		)	—			(18		)	(5		)
Unrealized gains, net	55			156			46			272
Other-than-temporary impairments	(15		)	(7		)	(44		)	(30		)
Interest, dividends, contributions and other	8			25			39			114
Balance at end of period	$	4,332		$	3,997		$	4,332		$	3,997