Employee Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2017
Components of Net Periodic Benefit Costs:
Defined Benefit Plans		$ 34	$ 32	$ 133	$ 108
Other changes in plan assets and benefit obligations recognized in Other Comprehensive Income (Loss):
Net actuarial loss(1)		(50)	(113)	(59)	(336)
Amortization of prior service credit	[1]	(2)	(3)	(7)	(8)
Amortization of net actuarial loss	[1]	50	40	160	133
Pension Plan [Member]
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer				717	102	$ 178
Pension Plan [Member] | Forecast
Contributions [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year							$ 835
Pension Plan [Member] | Domestic Plan [Member]
Components of Net Periodic Benefit Costs:
Service cost		0	1	2	3
Interest cost		31	32	97	103
Expected return on plan assets		(35)	(34)	(96)	(108)
Recognized net actuarial loss		5	8	16	20
Amortization of prior service credit		0	0	(1)	(1)
Recognized settlement loss		23	16	84	62
Defined Benefit Plans		24	23	102	79
Defined contribution plans		6	8	19	23
Net Periodic Benefit Cost		30	31	121	102
Other changes in plan assets and benefit obligations recognized in Other Comprehensive Income (Loss):
Net actuarial loss(1)	[2]	50	113	70	370
Amortization of prior service credit		0	0	1	1
Amortization of net actuarial loss		(28)	(24)	(100)	(82)
Total Recognized in Other Comprehensive Income (Loss)(2)	[3]	22	89	(29)	289
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss)		52	120	92	391
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer				668	17	24
Pension Plan [Member] | Domestic Plan [Member] | Forecast
Contributions [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year							674
Pension Plan [Member] | Domestic Plan [Member] | Qualified Plan [Member]
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer		650
Pension Plan [Member] | Domestic Plan [Member] | Qualified Plan [Member] | Original Forecast
Contributions [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year							135
Pension Plan [Member] | Domestic Plan [Member] | Qualified Plan [Member] | Incremental
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer		500
Pension Plan [Member] | Domestic Plan [Member] | Minimum Funding Requirement [Member]
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer		15
Pension Plan [Member] | Domestic Plan [Member] | Voluntary Contributions [Member]
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer		635
Pension Plan [Member] | Foreign Plan [Member]
Components of Net Periodic Benefit Costs:
Service cost		5	7	20	23
Interest cost		43	49	120	150
Expected return on plan assets		(57)	(61)	(164)	(190)
Recognized net actuarial loss		20	15	58	49
Amortization of prior service credit		(1)	(1)	(3)	(3)
Recognized settlement loss		0	0	0	0
Defined Benefit Plans		10	9	31	29
Defined contribution plans		8	6	22	22
Net Periodic Benefit Cost		18	15	53	51
Other changes in plan assets and benefit obligations recognized in Other Comprehensive Income (Loss):
Net actuarial loss(1)	[2]	0	0	0	0
Amortization of prior service credit		1	1	3	3
Amortization of net actuarial loss		(21)	(15)	(59)	(49)
Total Recognized in Other Comprehensive Income (Loss)(2)	[3]	(20)	(14)	(56)	(46)
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss)		(2)	1	(3)	5
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer				49	85	154
Pension Plan [Member] | Foreign Plan [Member] | Forecast
Contributions [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year							161
Retiree Health [Member]
Components of Net Periodic Benefit Costs:
Service cost		2	1	4	4
Interest cost		7	9	21	25
Expected return on plan assets		0	0	0	0
Recognized net actuarial loss		0	0	0	1
Amortization of prior service credit		(1)	(2)	(3)	(4)
Recognized settlement loss		0	0	0	0
Defined Benefit Plans		8	8	22	26
Net Periodic Benefit Cost		8	8	22	26
Other changes in plan assets and benefit obligations recognized in Other Comprehensive Income (Loss):
Net actuarial loss(1)	[2]	0	0	(11)	(34)
Amortization of prior service credit		1	2	3	4
Amortization of net actuarial loss		(1)	0	(1)	(1)
Total Recognized in Other Comprehensive Income (Loss)(2)	[3]	0	2	(9)	(31)
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Loss)		$ 8	$ 10	13	(5)
Contributions [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer				$ 49	$ 46	$ 61
Retiree Health [Member] | Forecast
Contributions [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year							$ 65

[1] Reclassified to Total Net Periodic Benefit Cost - refer to Note 14 - Employee Benefit Plans for additional information.

[2] The net actuarial loss (gain) for U.S. Plans primarily reflects (i) the remeasurement of our primary U.S. pension plans as a result of the payment of periodic settlements and (ii) adjustments for the actuarial valuation results based on January 1st plan census data.

[3] Amounts represent the pre-tax effect included within Other comprehensive Income (Loss). Refer to Note 16 - Other Comprehensive Income (Loss) for related tax effects and the after-tax amounts.