Pension Plans, Retirement Benefits and Savings Plans (details) - Additional Pension Disclosures (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	$ 494,000,000	$ (647,000,000)	$ 69,000,000
Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	3,510,000,000	3,050,000,000
Aggregate projected benefit obligation for pension plans with an accumulated benefit obligation in excess of plan assets	3,530,000,000	123,000,000
Aggregate accumulated benefit obligation for pension plans with an accumulated benefit obligation in excess of plan assets	3,430,000,000	121,000,000
Fair value of plan assets for pension plans with an accumulated benefit obligation in excess of plan assets	3,270,000,000	33,000,000
Components of net periodic benefit cost
Service cost	110,000,000	118,000,000	113,000,000
Interest cost on benefit obligation	150,000,000	132,000,000	138,000,000
Expected return on plan assets	(218,000,000)	(208,000,000)	(187,000,000)
Net periodic benefit cost, curtailment	(1,000,000)
Net periodic benefit cost, settlement	2,000,000
Net periodic benefit cost, amortization of unrecognized net actuarial loss (gain)	65,000,000	107,000,000	89,000,000
Net periodic benefit cost	108,000,000	149,000,000	153,000,000
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, prior service benefit	(8,000,000)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	516,000,000	(518,000,000)	176,000,000
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, curtailment	(2,000,000)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, settlement	(2,000,000)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial gain (loss)	(65,000,000)	(107,000,000)	(89,000,000)
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	439,000,000	(625,000,000)	87,000,000
Total other changes recognized in net periodic benefit cost and other comprehensive income	547,000,000	(476,000,000)	240,000,000
Estimated net actuarial loss that will be amortized from other comprehensive income into net periodic benefit cost over the next fiscal year	96,000,000
Estimated prior service benefit to be amortized over the next fiscal year	1,000,000
Estimated Future Benefit Payments
Benefits expected to be paid, 2015	205,000,000
Benefits expected to be paid, 2016	211,000,000
Benefits expected to be paid, 2017	215,000,000
Benefits expected to be paid, 2018	224,000,000
Benefits expected to be paid, 2019	234,000,000
Benefits expected to be paid, 2020 through 2024	1,203,000,000
Qualified Domestic Pension Plan [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	3,290,000,000	2,850,000,000
Components of net periodic benefit cost
Service cost	104,000,000	112,000,000
Interest cost on benefit obligation	140,000,000	124,000,000
Nonqualified and Foreign Pension Plans [Member]
Defined benefit plan disclosure
Total accumulated benefit obligation	220,000,000	200,000,000
Components of net periodic benefit cost
Service cost	6,000,000	6,000,000
Interest cost on benefit obligation	10,000,000	8,000,000
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost
Interest cost on benefit obligation	10,000,000	9,000,000	12,000,000
Expected return on plan assets		(1,000,000)	(1,000,000)
Net periodic benefit cost, amortization of unrecognized prior service benefit	(2,000,000)	(2,000,000)
Net periodic benefit cost, amortization of unrecognized net actuarial loss (gain)	(3,000,000)		(1,000,000)
Net periodic benefit cost	5,000,000	6,000,000	10,000,000
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, net actuarial loss (gain)	50,000,000	(24,000,000)	11,000,000
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, plan amendments			(31,000,000)
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of prior service benefit	2,000,000	2,000,000
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income, amortization of net actuarial gain (loss)	3,000,000		1,000,000
Total other changes in benefit plan assets and benefit obligations recognized in other comprehensive income	55,000,000	(22,000,000)	(19,000,000)
Total other changes recognized in net periodic benefit cost and other comprehensive income	60,000,000	(16,000,000)	(9,000,000)
Estimated prior service benefit to be amortized over the next fiscal year	3,000,000
Estimated Future Benefit Payments
Benefits expected to be paid, 2015	15,000,000
Benefits expected to be paid, 2016	15,000,000
Benefits expected to be paid, 2017	15,000,000
Benefits expected to be paid, 2018	15,000,000
Benefits expected to be paid, 2019	15,000,000
Benefits expected to be paid, 2020 through 2024	76,000,000
Postretirement Benefit Plans [Member] | Maxiumum [Member]
Other changes in benefit plan assets and benefit obligations recognized in other comprehensive income:
Estimated net actuarial loss that will be amortized from other comprehensive income into net periodic benefit cost over the next fiscal year	$ 1,000,000