Employee Benefits (Details 2) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended
	Apr. 02, 2009 item	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Percentage of the Company's projected benefit obligation		94.00%
U.K. and non-U.S.
Change in projected benefit obligation
Balance at the beginning of the Period		$ 5,583	$ 4,812
Service cost		15	19	15
Interest cost		265	267	249
Participant contributions		1	1
Plan amendment			12
Plan transfer and acquisitions			17
Actuarial loss (gain)		(139)	(32)
Benefit payments		(195)	(181)
Change in discount rate		562	651
Foreign currency revaluation		175	17
Balance at the end of the period		6,267	5,583	4,812
Accumulated benefit obligation at end of year		6,186	5,508
Change in fair value of plan assets
Balance at the beginning of the period		5,098	4,288
Actual return on plan assets		392	595
Participant contributions		1	1
Employer contributions		412	364
Plan transfer and acquisitions			13
Benefit payments		(195)	(181)
Foreign currency revaluation		161	18
Balance at the end of the period		5,869	5,098	4,288
Market related value at the end of the year		5,869	5,098
Funded status		(398)	(485)
Unrecognized prior-service cost (credit)		28	28
Unrecognized loss (gain)		2,472	2,109
Net amount recognized		2,102	1,652
Canadian pension plan
Defined Benefit Plan Disclosure
Employees that will be affected due to a change in pension plan in 2010				950
U.S. Pension Plan
Defined Benefit Plan Disclosure
Employees affected due to a change in pension plan	6,000
Change in projected benefit obligation
Balance at the beginning of the Period		2,657	2,376
Interest cost		119	122	124
Actuarial loss (gain)		29	51
Benefit payments		(123)	(115)
Change in discount rate		202	223
Balance at the end of the period		2,884	2,657	2,376
Accumulated benefit obligation at end of year		2,884	2,657
Change in fair value of plan assets
Balance at the beginning of the period		1,325	1,244
Actual return on plan assets		203	83
Employer contributions		226	113
Benefit payments		(123)	(115)
Balance at the end of the period		1,631	1,325	1,244
Market related value at the end of the year		1,566	1,410
Funded status		(1,253)	(1,332)
Unrecognized loss (gain)		1,591	1,480
Net amount recognized		338	148
U.S. and Canadian Other Post-Retirement Benefits
Change in projected benefit obligation
Accumulated benefit obligation at end of year		134	134
Change in fair value of plan assets
Balance at the end of the period		20	20
Funded status		(114)	(114)
Unrecognized prior-service cost (credit)		(15)	(8)
Unrecognized loss (gain)		37	25
Net amount recognized		$ (92)	$ (97)