Retirement Benefits - Fair Value Unobservable (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	$ 2,415	$ 2,426
Actual return on plan assets:
Relating to assets still held at the reporting date	292	217
Relating to assets sold during the period	(1)
Purchases	752	689
Sales	(167)	(6)
Settlements	(198)	(160)
Transfers into (out of) Level 3	(623)	(751)
Fair value of net plan assets at the Ending of year	2,470	2,415
Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	108	165
Actual return on plan assets:
Relating to assets still held at the reporting date	12	14
Purchases	4	123
Sales	(1)
Settlements	(4)	(1)
Transfers into (out of) Level 3	(4)	(193)
Fair value of net plan assets at the Ending of year	115	108
Hedge Fund Investments [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	1,235	1,525
Actual return on plan assets:
Relating to assets still held at the reporting date	143	138
Relating to assets sold during the period	3
Purchases	360	447
Sales	(76)	(6)
Settlements	(3)	(4)
Transfers into (out of) Level 3	(623)	(865)
Fair value of net plan assets at the Ending of year	1,039	1,235
Hedge Fund Investments [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	12	157
Actual return on plan assets:
Relating to assets still held at the reporting date	1	11
Purchases	0	32
Sales	(1)
Settlements	(4)
Transfers into (out of) Level 3	(4)	(188)
Fair value of net plan assets at the Ending of year	4	12
Commingled Funds In Private Equity Investments [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	754	672
Actual return on plan assets:
Relating to assets still held at the reporting date	86	55
Purchases	123	108
Sales	0
Settlements	(157)	(128)
Transfers into (out of) Level 3	0	47
Fair value of net plan assets at the Ending of year	806	754
Commingled Funds In Private Equity Investments [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	1	1
Actual return on plan assets:
Purchases	1	0
Fair value of net plan assets at the Ending of year		1
Commingled Funds In Equity And Fixed Income Securities [Member] | Pension Plans Defined Benefit [Member]
Actual return on plan assets:
Purchases	41
Fair value of net plan assets at the Ending of year	41
Commingled Funds In Equity And Fixed Income Securities [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Actual return on plan assets:
Fair value of net plan assets at the Ending of year	2
Commingled Funds In Direct Real Estate [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	426	229
Actual return on plan assets:
Relating to assets still held at the reporting date	63	24
Relating to assets sold during the period	(4)
Purchases	226	134
Sales	(91)	0
Settlements	(38)	(28)
Transfers into (out of) Level 3	0	67
Fair value of net plan assets at the Ending of year	582	426
Commingled Funds In Direct Real Estate [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at the begining of year	95	7
Actual return on plan assets:
Relating to assets still held at the reporting date	11	3
Purchases	3	91
Settlements	0	(1)
Transfers into (out of) Level 3	0	(5)
Fair value of net plan assets at the Ending of year	109	95
CommingledFundsInEquitySecuritiesMember [Member] | Pension Plans Defined Benefit [Member]
Actual return on plan assets:
Purchases	2
Fair value of net plan assets at the Ending of year	$ 2