Other Investments (Tables)

6 Months Ended

Jun. 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)		June 30, 2013			December 31, 2012			June 30, 2013			December 31, 2012
Stocks	—	$	728		$	978		$	2,085		$	2,271
Municipal bonds	2051	504			518			592			644
U.S. government and agency securities	2043	975			547			1,025			603
Corporate bonds	2054	293			324			347			410
Short-term investments, primarily cash equivalents	One-year	274			117			280			121
Total investments		2,774			2,484			4,329			4,049
Net payables		(148		)	(1		)	(148		)	(1		)
Total nuclear decommissioning trusts		$	2,626		$	2,483		$	4,181		$	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 June 30,						Six months ended June 30,
(in millions)	2013			2012			2013			2012
Balance at beginning of period	$	4,246		$	3,853		$	4,048		$	3,592
Gross realized gains	137			15			142			40
Gross realized losses	(1		)	(1		)	(2		)	(5		)
Unrealized gains (losses), net	(185		)	(67		)	(9		)	116
Other-than-temporary impairments	(21		)	(19		)	(29		)	(23		)
Interest, dividends, contributions and other	5			29			31			90
Balance at end of period	$	4,181		$	3,810		$	4,181		$	3,810