Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Plan amendments			$ (129)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Ending balance as of December 31, 2012	1,851		1,505
Amounts recognized in Consolidated Balance Sheets
Non-current liabilities	(529)		(511)
Retirement Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefit obligation at beginning of year	1,834		1,794
Service cost	24		67		61
Interest cost	93		99		94
Plan participant's contributions	1		1
Actuarial loss (gain)	287		59
Gross benefits paid	(71)		(63)
Plan amendments	0	[1]	(129)	[1]
Foreign currency effect	11		3
Federal subsidy benefits received	0		0
Other adjustments	(8)		3
Net benefit obligation at end of year	2,171		1,834		1,794
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance as of December 31, 2011	1,505		1,567
Actual return on plan assets	212		(31)
Employer contributions	193		29
Plan participant's contributions	1		1
Foreign currency effect	11		2
Ending balance as of December 31, 2012	1,851		1,505		1,567
Funded status	(320)		(329)
Amounts recognized in Consolidated Balance Sheets
Non-current assets	97		68
Current liabilities	(6)		(6)
Non-current liabilities	(411)		(391)
Amounts Recognized in Consolidated Balance Sheet, Total	(320)		(329)
Accumulated benefit obligation	2,093		1,773
Plans with accumulated benefit obligation in excess of the fair value of plan assets
Projected benefit obligation	1,773		1,487
Accumulated benefit obligation	1,756		1,480
Fair value of plan assets	1,356		1,090
Amounts recognized in accumulated other comprehensive loss, net of tax
Net actuarial loss	455		359
Prior service credit	(4)		(6)
Total recognized	451		353
Postretirement Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefit obligation at beginning of year	129		144
Service cost	3		3		3
Interest cost	5		6		7
Plan participant's contributions	5		5
Actuarial loss (gain)	3		(14)
Gross benefits paid	(17)		(16)
Plan amendments	0	[1]	0	[1]
Foreign currency effect	0		0
Federal subsidy benefits received	1		1
Other adjustments	0		0
Net benefit obligation at end of year	129		129		144
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance as of December 31, 2011	0		0
Actual return on plan assets	0		0
Employer contributions	12		10
Plan participant's contributions	5		6
Foreign currency effect	0		0
Ending balance as of December 31, 2012	0		0		0
Funded status	(129)		(129)
Amounts recognized in Consolidated Balance Sheets
Non-current assets	0		0
Current liabilities	(11)		(9)
Non-current liabilities	(118)		(120)
Amounts Recognized in Consolidated Balance Sheet, Total	(129)		(129)
Amounts recognized in accumulated other comprehensive loss, net of tax
Net actuarial loss	(3)		(5)
Prior service credit	(1)		(2)
Total recognized	$ (4)		$ (7)

[1] In December 2011, our Board of Directors approved a plan amendment that froze our U.S. ERP effective on April 1, 2012. This amendment decreased our pension benefit liabilities by $129 million, and resulted in an after-tax decrease in accumulated other comprehensive loss of $82 million. We also recorded an immaterial amount of pension plan curtailment expense in 2011 as a result of the plan amendment.