Retirement Plans and Other Benefits (Tables)

9 Months Ended

Sep. 30, 2014

Compensation and Retirement Disclosure [Abstract]

Schedule of net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged or amortized to the regulatory asset)

The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged or amortized to the regulatory asset) (dollars in millions):

	Pension Benefits												Other Benefits
	Three Months Ended   September 30,						Nine Months Ended   September 30,						Three Months Ended   September 30,						Nine Months Ended   September 30,
	2014			2013			2014			2013			2014			2013			2014			2013
Service cost — benefits earned during the period	$	13		$	16		$	40		$	48		$	5		$	6		$	14		$	18
Interest cost on benefit obligation	32			28			97			84			12			10			35			31
Expected return on plan assets	(39		)	(36		)	(119		)	(110		)	(13		)	(11		)	(38		)	(34		)
Amortization of:
Prior service cost	—			—			—			1			—			—			—			—
Net actuarial loss	3			10			8			30			—			3			—			8
Net periodic benefit cost	$	9		$	18		$	26		$	53		$	4		$	8		$	11		$	23
Portion of cost charged to expense	$	5		$	10		$	16		$	29		$	3		$	5		$	8		$	14

Schedule of Assumptions Used

The following table provides the assumptions used for the remeasurement at September 30, 2014:

Discount rate	4.41	%
Long-term rate of return	4.25	%
Initial healthcare cost trend rate (pre-65 participants)	7.50	%
Ultimate healthcare cost trend rate (pre-65 participants)	5.00	%
Number of years to ultimate trend rate	4
Medical cost subsidy trend rate (post-65 participants)	5.00	%