Pension and Other Postretirement Employee Benefit Plans - Changes In Level 3 Fair Value Measurements (Details 10) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Pension Plans, U.S. [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	$ 13,012	$ 10,472	$ 10,828
Defined Benefit Pension Plans, U.S. [Member] | Equities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	3,933
Defined Benefit Pension Plans, U.S. [Member] | Common/collective trust funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Transfers in and/or out of level 3		0
Fair value of plan assets, end of year	2,271	1,728
Defined Benefit Pension Plans, U.S. [Member] | Limited Partnerships [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	4,565	3,909
Defined Benefit Pension Plans, U.S. [Member] | Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Transfers in and/or out of level 3		(56)
Fair value of plan assets, end of year	2,044	1,972
Defined Benefit Pension Plans, U.S. [Member] | Limited partnerships - Private equity funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	1,743	1,367
Defined Benefit Pension Plans, U.S. [Member] | Real Estate [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	467	306
Defined Benefit Pension Plans, U.S. [Member] | Real Assets [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	311	264
Defined Benefit Pension Plans, U.S. [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	1,115	546
Defined Benefit Pension Plans, U.S. [Member] | Plan Asset Categories Other [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	461	589
Defined Benefit Pension Plans, Non-U.S. [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	3,330	2,989	2,647
Defined Benefit Pension Plans, Non-U.S. [Member] | Equities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	750
Defined Benefit Pension Plans, Non-U.S. [Member] | Common/collective trust funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	254	308
Defined Benefit Pension Plans, Non-U.S. [Member] | Limited Partnerships [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Defined Benefit Pension Plans, Non-U.S. [Member] | Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Defined Benefit Pension Plans, Non-U.S. [Member] | Limited partnerships - Private equity funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Defined Benefit Pension Plans, Non-U.S. [Member] | Real Estate [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Defined Benefit Pension Plans, Non-U.S. [Member] | Real Assets [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Defined Benefit Pension Plans, Non-U.S. [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	765	958
Defined Benefit Pension Plans, Non-U.S. [Member] | Plan Asset Categories Other [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	88	139
OPEB Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	1,563	1,435	1,381
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	3,608	3,278	2,368
Realized gains/(losses)	78	88	5
Unrealized gains/(losses)	150	104	101
Purchases, sales and settlements, net	471	137	712
Transfers in and/or out of level 3	4	1	92
Fair value of plan assets, end of year	4,311	3,608	3,278
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Equities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	1	0	0
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	(1)	0	0
Purchases, sales and settlements, net	0	0	0
Transfers in and/or out of level 3	4	1	0
Fair value of plan assets, end of year	4	1	0
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Common/collective trust funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	202	194	284
Realized gains/(losses)	2	35	0
Unrealized gains/(losses)	22	1	(90)
Purchases, sales and settlements, net	(27)	(28)	0
Transfers in and/or out of level 3	0		0
Fair value of plan assets, end of year	199	202	194
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Limited Partnerships [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	2,976	2,696	1,750
Realized gains/(losses)	76	53	5
Unrealized gains/(losses)	136	62	138
Purchases, sales and settlements, net	499	165	712
Transfers in and/or out of level 3	0	0	91
Fair value of plan assets, end of year	3,687	2,976	2,696
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	1,039	1,160	680
Realized gains/(losses)	1	(16)	(1)
Unrealized gains/(losses)	71	27	14
Purchases, sales and settlements, net	55	(76)	388
Transfers in and/or out of level 3	0		79
Fair value of plan assets, end of year	1,166	1,039	1,160
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Limited partnerships - Private equity funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	1,367	1,232	874
Realized gains/(losses)	59	56	3
Unrealized gains/(losses)	54	2	108
Purchases, sales and settlements, net	263	77	235
Transfers in and/or out of level 3	0	0	12
Fair value of plan assets, end of year	1,743	1,367	1,232
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Real Estate [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	306	304	196
Realized gains/(losses)	16	8	3
Unrealized gains/(losses)	1	40	16
Purchases, sales and settlements, net	144	14	89
Transfers in and/or out of level 3	0	(60)	0
Fair value of plan assets, end of year	467	306	304
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Real Assets [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	264	0	0
Realized gains/(losses)	0	5	0
Unrealized gains/(losses)	10	(7)	0
Purchases, sales and settlements, net	37	150	0
Transfers in and/or out of level 3	0	116	0
Fair value of plan assets, end of year	311	264	0
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	2	1	0
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	0	0	0
Purchases, sales and settlements, net	(1)	1	0
Transfers in and/or out of level 3	0	0	1
Fair value of plan assets, end of year	1	2	1
Level 3 [Member] | Defined Benefit Pension Plans, U.S. [Member] | Plan Asset Categories Other [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	427	387	334
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	(7)	41	53
Purchases, sales and settlements, net	0	(1)	0
Transfers in and/or out of level 3	0	0	0
Fair value of plan assets, end of year	420	427	387
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	0	0	13
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	0	0	(1)
Purchases, sales and settlements, net	0	0	(12)
Transfers in and/or out of level 3	0	0	0
Fair value of plan assets, end of year	0	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Equities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Common/collective trust funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Limited Partnerships [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Limited partnerships - Private equity funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Real Estate [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Real Assets [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, end of year	0	0
Level 3 [Member] | Defined Benefit Pension Plans, Non-U.S. [Member] | Plan Asset Categories Other [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	0	0	13
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	0	0	(1)
Purchases, sales and settlements, net	0	0	(12)
Transfers in and/or out of level 3	0	0	0
Fair value of plan assets, end of year	0	0	0
Level 3 [Member] | OPEB Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	1,427	1,381	1,269
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	127	70	137
Purchases, sales and settlements, net	0	(24)	(25)
Transfers in and/or out of level 3	0	0	0
Fair value of plan assets, end of year	1,554	1,427	1,381
Level 3 [Member] | OPEB Plans [Member] | COLI [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning of year	1,427	1,381	1,269
Realized gains/(losses)	0	0	0
Unrealized gains/(losses)	127	70	137
Purchases, sales and settlements, net	0	(24)	(25)
Transfers in and/or out of level 3	0	0	0
Fair value of plan assets, end of year	$ 1,554	$ 1,427	$ 1,381