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	$ (1)	$ 58
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	205	155
Realized gains (losses)	2	(5)
Unrealized gains (losses)	21	14
Purchases	41	122
Sales	(9)	(81)
Ending Balance	260	205
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	23	8
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds and Similar Investments [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	119	95
Realized gains (losses)	0	6
Unrealized gains (losses)	14	0
Purchases	26	86
Sales	0	(68)
Ending Balance	159	119
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	14	6
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity and Other [Member]
Defined Benefit Plans Fair Value Measurements Using Significant Unobservale Inputs [Line Items]
Beginning Balance	86	60
Realized gains (losses)	2	(11)
Unrealized gains (losses)	7	14
Purchases	15	36
Sales	(9)	(13)
Ending Balance	101	86
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	$ 9	$ 2