Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Benefit Plans
Maximum annual medical cost inflation after retirement for Company's share of retiree medical benefits cost for non Medicare-eligible retirees (as a percent)	5.00%
Items not yet recognized as a component of net periodic cost
Deferred income taxes	$ (597,000,000)	$ 722,000,000
Unrecognized pension and other postretirement benefit cost	1,729,000,000	1,427,000,000
Pension plan assets
Insurance Reserves Recognized in Accumulated Other Comprehensive Income	(771,000,000)	(594,000,000)
Pension benefits
Components of net periodic cost
Fair value of plan assets	5,398,000,000	4,675,000,000	4,669,000,000
Less: Benefit obligation	6,727,000,000	5,831,000,000	5,545,000,000
Funded status	(1,329,000,000)	(1,156,000,000)
Items not yet recognized as a component of net periodic cost
Net actuarial loss (gain)	2,892,000,000	2,546,000,000
Prior service credit	(1,000,000)	(3,000,000)
Unrecognized pension and other postretirement benefit cost, pre-tax	2,891,000,000	2,543,000,000
Deferred income taxes	(1,012,000,000)	(890,000,000)
Unrecognized pension and other postretirement benefit cost	1,879,000,000	1,653,000,000
Increase (decrease) in defined benefit net actuarial loss arising during the period	346,000,000
Change in items not yet recognized as a component of defined benefit plans, net periodic cost
Items not yet recognized as a component of net periodic cost, at the beginning of the period	2,543,000,000
Net actuarial loss (gain) arising during the period	555,000,000
Net actuarial (loss) gain amortized to net periodic benefit cost	(211,000,000)
Prior service credit amortized to net periodic benefit cost	2,000,000
Translation adjustment and other	2,000,000
Items not yet recognized as a component of net periodic cost, at the end of the period	2,891,000,000	2,543,000,000
Estimates of the net actuarial loss (gain) and prior service credit expected to be recognized as a component of net periodic benefit cost during 2012
Net actuarial loss (gain)	261,000,000
Prior service credit	(2,000,000)
Accumulated benefit obligation (ABO)	6,090,000,000	5,160,000,000
Company's Pension Plans with an ABO in excess of plan assets
Company's pension plans with ABO in excess of plan assets, aggregate projected benefit obligation	6,350,000,000	5,510,000,000
Company's pension plans with ABO in excess of plan assets, aggregate accumulated benefit obligation	5,750,000,000	4,850,000,000
Company's pension plans with ABO in excess of plan assets, aggregate fair value of plan assets	5,020,000,000	4,330,000,000
Defined benefit plans' accrued benefit costs related to certain unfunded and non-qualified plans	146,000,000	142,000,000
Change in benefit obligation
Benefit obligation, beginning of year	5,831,000,000	5,545,000,000
Service cost	152,000,000	151,000,000	150,000,000
Interest cost	298,000,000	322,000,000	320,000,000
Participant contributions	1,000,000	1,000,000
Actuarial loss	756,000,000	337,000,000
Benefits paid	(312,000,000)	(511,000,000)
Translation adjustment and other	1,000,000	(14,000,000)
Benefit obligation, end of year	6,727,000,000	5,831,000,000	5,545,000,000
Components of net periodic cost
Service cost	152,000,000	151,000,000	150,000,000
Interest cost	298,000,000	322,000,000	320,000,000
Expected return on plan assets	(393,000,000)	(367,000,000)	(331,000,000)
Amortization of prior service credit	(2,000,000)	(2,000,000)	(2,000,000)
Amortization of net actuarial loss (gain)	178,000,000	154,000,000	160,000,000
Settlement loss	33,000,000	46,000,000	48,000,000
Net periodic cost (credit)	266,000,000	304,000,000	345,000,000
Weighted average assumptions used to determine net pension cost and net postretirement benefit cost
Discount rate (as a percent)	5.25%	6.00%	6.25%
Rate of increase in compensation levels, low end of the range (as a percent)		4.00%	4.00%
Rate of increase in compensation levels, high end of the range (as a percent)		4.50%	4.50%
Rate of increase in compensation levels	4.50%
Expected long-term rate of return on plan assets (as a percent)	8.50%	8.50%	8.50%
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.00%	5.25%
Rate of increase in compensation levels, low end of the range (as a percent)		4.00%
Rate of increase in compensation levels, high end of range (as a percent)		4.50%
Rate of increase in compensation levels	3.50%
Pension plan assets
Fair value of plan assets, beginning of year	4,675,000,000	4,669,000,000
Actual return on plan assets	594,000,000	267,000,000
Employer contribution	439,000,000	264,000,000
Benefits paid	(312,000,000)	(511,000,000)
Translation adjustment and other	2,000,000	(14,000,000)
Fair value of plan assets, end of year	5,398,000,000	4,675,000,000	4,669,000,000
Postretirement benefits
Components of net periodic cost
Less: Benefit obligation	803,000,000	716,000,000	628,000,000
Funded status	(803,000,000)	(716,000,000)
Items not yet recognized as a component of net periodic cost
Net actuarial loss (gain)	(115,000,000)	(211,000,000)
Prior service credit	(129,000,000)	(152,000,000)
Unrecognized pension and other postretirement benefit cost, pre-tax	(244,000,000)	(363,000,000)
Deferred income taxes	94,000,000	137,000,000
Unrecognized pension and other postretirement benefit cost	(150,000,000)	(226,000,000)
Increase (decrease) in defined benefit net actuarial loss arising during the period	(96,000,000)
Increase (decrease) in defined benefit plan	(23,000,000)
Change in items not yet recognized as a component of defined benefit plans, net periodic cost
Items not yet recognized as a component of net periodic cost, at the beginning of the period	(363,000,000)
Net actuarial loss (gain) arising during the period	76,000,000
Net actuarial (loss) gain amortized to net periodic benefit cost	20,000,000
Prior service credit amortized to net periodic benefit cost	23,000,000
Items not yet recognized as a component of net periodic cost, at the end of the period	(244,000,000)	(363,000,000)
Estimates of the net actuarial loss (gain) and prior service credit expected to be recognized as a component of net periodic benefit cost during 2012
Net actuarial loss (gain)	(12,000,000)
Prior service credit	(23,000,000)
Change in benefit obligation
Benefit obligation, beginning of year	716,000,000	628,000,000
Service cost	13,000,000	11,000,000	12,000,000
Interest cost	36,000,000	37,000,000	40,000,000
Participant contributions	20,000,000	20,000,000
Actuarial loss	76,000,000	82,000,000
Benefits paid	(59,000,000)	(61,000,000)
Translation adjustment and other	1,000,000	(1,000,000)
Benefit obligation, end of year	803,000,000	716,000,000	628,000,000
Components of net periodic cost
Service cost	13,000,000	11,000,000	12,000,000
Interest cost	36,000,000	37,000,000	40,000,000
Amortization of prior service credit	(23,000,000)	(23,000,000)	(22,000,000)
Amortization of net actuarial loss (gain)	(20,000,000)	(30,000,000)	(22,000,000)
Settlement loss		1,000,000
Net periodic cost (credit)	6,000,000	(4,000,000)	8,000,000
Weighted average assumptions used to determine net pension cost and net postretirement benefit cost
Discount rate (as a percent)	5.25%	6.00%	6.25%
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.25%	5.25%
Defined benefit plan, assumed health care cost trend rates
Defined Benefit plan, Weighted average health care cost trend rate (as a percent)	7.20%
Defined Benefit plan, ultimate health care cost trend rate in 2024 and thereafter (as a percent)	4.50%
Increase in the total of service and interest cost components of net periodic benefit cost due to one percentage-point increase in assumed health care cost trend rates	3,000,000
Increase in APBO due to one percentage-point increase in assumed health care cost trend rates	28,000,000
Decrease in APBO due to one percentage-point decrease in assumed health care cost trend rates	2,000,000
Decrease in the total of service and interest cost components of net periodic benefit cost due to one percentage-point decrease in assumed health care cost trend rates	25,000,000
Pension plan assets
Employer contribution	39,000,000	41,000,000
Benefits paid	$ (59,000,000)	$ (61,000,000)