Employee Benefit Plans - Net Periodic Benefit (Income) Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postemployment Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net service cost	$ 34	$ 16	$ 17
Interest cost	2	3	3
Amortization of prior service cost	(6)	(6)	(4)
Actuarial loss (gain)	(6)	(7)	0
Net benefit cost	24	6	16
Restructuring severance cost	0	4	1
Net periodic benefit cost	24	10	17
Postretirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	1	1	1
Amortization of prior service cost	(6)	(14)	(18)
Actuarial loss (gain)	2	2	2
Net periodic benefit cost	(3)	(11)	(15)
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net service cost	8	7	12
Interest cost	91	118	129
Expected return on plan assets	(92)	(108)	(132)
Amortization of prior service cost	1	1	1
Actuarial loss (gain)	28	85	29
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	(2)
Settlement charge	0	0	427
Net periodic benefit cost	36	103	464
Company contributions	25	31
U.S. Pension Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net service cost	0	0	0
Interest cost	71	90	87
Expected return on plan assets	(57)	(72)	(72)
Amortization of prior service cost	0	0	0
Actuarial loss (gain)	28	16	27
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	0
Settlement charge	0	0	0
Net periodic benefit cost	42	34	42
Company contributions	0	0
International Pension Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net service cost	8	7	12
Interest cost	20	28	42
Expected return on plan assets	(35)	(36)	(60)
Amortization of prior service cost	1	1	1
Actuarial loss (gain)	0	69	2
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	(2)
Settlement charge	0	0	427
Net periodic benefit cost	(6)	69	$ 422
Company contributions	25	$ 31
Voluntary lump sum payment [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Benefits Paid	130
Voluntary lump sum payment and single premium group annuity contract [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Actuarial loss (gain)	(25)
Single premium group annuity contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Benefits Paid	$ 190