Employee Benefit Plans - Funded Status (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Domestic Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets	$ 1,171	$ 1,655
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	1,655	1,486
Defined Benefit Plan, Plan Assets Acquired	818	0
Contributions by Employer	71	114
Participant contributions	0	0
Actual Return on Plan Assets	359	194
Benefits Paid	(192)	(139)
Fair Value of Plan Assets, End of year	2,711	1,655	1,486
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	2,237	2,090
Defined Benefit Plan, Benefit Obligation, Acquisitions	823	0
Service Cost	24	25	28
Interest Cost	87	98	102
Actuarial Loss	(158)	163
Benefits Paid	(192)	(139)
Benefit Obligation, end of year	2,821	2,237	2,090
Accumulated Benefit Obligation	2,747	2,211
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(110)	(582)
Other assets	98	0
Other current liabilities	(19)	(12)
Other long-term liabilities	(189)	(570)
Amounts recognized on balance sheet	(110)	(582)
Supplemental Employee Retirement Plans [Abstract]
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Benefit Obligation	1,379	2,237
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	1,374	2,211
Domestic Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets	596	424
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	650	597
Defined Benefit Plan, Plan Assets Acquired	110	0
Contributions by Employer	8	10
Participant contributions	8	9
Actual Return on Plan Assets	127	78
Benefits Paid	(51)	(44)
Fair Value of Plan Assets, End of year	852	650	597
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	845	773
Defined Benefit Plan, Benefit Obligation, Acquisitions	154	0
Service Cost	14	11	11
Interest Cost	33	36	41
Actuarial Loss	(16)	60
Benefits Paid	(51)	(44)
Benefit Obligation, end of year	987	845	773
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(135)	(195)
Other assets	21	13
Other current liabilities	0	0
Other long-term liabilities	(156)	(208)
Amounts recognized on balance sheet	(135)	(195)
Supplemental Employee Retirement Plans [Abstract]
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Benefit Obligation	751	632
UK Pension Plans [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets, Beginning of year	1,996	1,759
Contributions by Employer	79	79
Participant contributions	3	3
Actual Return on Plan Assets	138	147
Benefits Paid	(83)	(80)
Foreign Currency Exchange Rate Changes	44	88
Fair Value of Plan Assets, End of year	2,177	1,996	1,759
Change in Benefit Obligation [Roll Forward]
Benefit Obligation, beginning of year	2,047	1,773
Service Cost	22	19	19
Interest Cost	85	85	92
Actuarial Loss	70	157
Benefits Paid	(83)	(80)
Foreign currency exchange rate changes	41	90
Benefit Obligation, end of year	2,185	2,047	1,773
Accumulated Benefit Obligation	1,917	1,826
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status of plan	(8)	(51)
Other long-term liabilities	(8)	(51)
SERP [Member]
Supplemental Employee Retirement Plans [Abstract]
Life insurance, corporate or bank owned, amount	$ 235	$ 180