Employee Benefit Plans - Funded Status (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Domestic Pension Plans [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	$ 1,486	$ 1,506
Contributions by Employer	114	126
Participant contributions	0	0
Actual Return on Plan Assets	194	(13)
Benefits Paid	(139)	(133)
Fair Value of Plan Assets, End of year	1,655	1,486	1,506
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	2,090	1,974
Service Cost	25	28	29
Interest Cost	98	102	105
Plan Amendments	0	(4)
Actuarial Loss	163	123
Benefits Paid, Net of Medicare Subsidy	(139)	(133)
Benefit Obligation, end of year	2,237	2,090	1,974
Accumulated Benefit Obligation	2,211	2,060
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(582)	(604)
Other assets	0	0
Other current liabilities	(12)	(12)
Other long-term liabilities	(570)	(592)
Amounts recognized on balance sheet	(582)	(604)
Domestic Other Postretirement Plans [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	597	605
Contributions by Employer	10	30
Participant contributions	9	16
Actual Return on Plan Assets	78	0
Benefits Paid	(44)	(54)
Fair Value of Plan Assets, End of year	650	597	605
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	773	770
Service Cost	11	11	10
Interest Cost	36	41	42
Plan Amendments	0	(72)
Actuarial Loss	60	58
Benefits Paid, Net of Medicare Subsidy	(44)	(51)
Benefit Obligation, end of year	845	773	770
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(195)	(176)
Other assets	13	15
Other current liabilities	0	0
Other long-term liabilities	(208)	(191)
Amounts recognized on balance sheet	(195)	(176)
UK Pension Plans [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	1,759	1,633
Contributions by Employer	79	79
Participant contributions	3	4
Actual Return on Plan Assets	147	141
Benefits Paid	(80)	(85)
Foreign Currency Exchange Rate Changes	88	(13)
Fair Value of Plan Assets, End of year	1,996	1,759	1,633
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	1,773	1,655
Service Cost	19	19	15
Interest Cost	85	92	89
Actuarial Loss	157	101
Foreign currency exchange rate changes	90	(13)
Benefit Obligation, end of year	2,047	1,773	1,655
Accumulated Benefit Obligation	1,826	1,587
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(51)	(14)
Other long-term liabilities	(51)	(14)
SERP [Member]
Supplemental Employee Retirement Plans [Abstract]
Life insurance, corporate or bank owned, amount	$ 180	$ 170