Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements using Level 3 Inputs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
The amount of total gains (losses) included in net income attributed to the change in unrealized gains or losses related to assets still held at the end of the period	$ 2	$ 1
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	135	102
Realized gains (losses)	2	(3)
Unrealized gains (losses)	15	9
Purchases	37	81
Sales	(7)	(54)
Ending Balance	182	135
The amount of total gains (losses) included in net income attributed to the change in unrealized gains or losses related to assets still held at the end of the period	16	5
Other Postretirement Benefit Plans, Defined Benefit [Member] | Hedge Funds and Similar Investments [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	78	63
Realized gains (losses)	0	4
Unrealized gains (losses)	10	0
Purchases	23	56
Sales	0	(45)
Ending Balance	111	78
The amount of total gains (losses) included in net income attributed to the change in unrealized gains or losses related to assets still held at the end of the period	10	4
Other Postretirement Benefit Plans, Defined Benefit [Member] | Private Equity and Other [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	57	39
Realized gains (losses)	2	(7)
Unrealized gains (losses)	5	9
Purchases	14	25
Sales	(7)	(9)
Ending Balance	71	57
The amount of total gains (losses) included in net income attributed to the change in unrealized gains or losses related to assets still held at the end of the period	$ 6	$ 1