Employee Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts Recognized in the Consolidated Balance Sheets:
Pension and other benefit liabilities		$ (1,595)	$ (2,240)
Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation - ending		10,883
Change in Plan Assets:
Fair value of plan assets -beginning		8,158
Employer contributions		836
Fair Value of Plan Assets - ending		9,532	8,158
Net Funded Status		(1,351)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation - beginning		761	855
Service cost		5	6	$ 7
Interest cost	[1]	28	32	34
Plan participants' contributions		2	1
Actuarial loss (gain)		(16)	(75)
Currency exchange rate changes		10	4
Plan Amendments/Curtailments		0	0
Benefits paid/settlements		(66)	(62)
Other		(1)	0
Benefit obligation - ending		723	761	855
Change in Plan Assets:
Fair value of plan assets -beginning		0	0
Actual return on plan assets		0	0
Employer contributions		64	61
Plan participants' contributions		2	1
Currency exchange rate changes		0	0
Benefits paid/settlements		(66)	(62)
Other		0	0
Fair Value of Plan Assets - ending		0	0	0
Net Funded Status	[2]	(723)	(761)
Amounts Recognized in the Consolidated Balance Sheets:
Other long-term assets		0	0
Accrued compensation and benefit costs		(61)	(63)
Pension and other benefit liabilities		0	0
Post-retirement medical benefits		(662)	(698)
Net Amounts Recognized		(723)	(761)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial loss		22	37
Prior service credit		(26)	(29)
Total Pre-tax Loss		(4)	8
Domestic Plan [Member] | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation - beginning		4,161	4,126
Service cost		2	4	4
Interest cost	[1]	226	184	80
Plan participants' contributions		0	0
Actuarial loss (gain)		392	114
Currency exchange rate changes		0	0
Plan Amendments/Curtailments		0	0
Benefits paid/settlements		(606)	(275)
Other		5	8
Benefit obligation - ending		4,180	4,161	4,126
Change in Plan Assets:
Fair value of plan assets -beginning		2,774	2,806
Actual return on plan assets		381	220
Employer contributions		675	24
Plan participants' contributions		0	0
Currency exchange rate changes		0	0
Benefits paid/settlements		(606)	(275)
Other		0	(1)
Fair Value of Plan Assets - ending		3,224	2,774	2,806
Net Funded Status	[2]	(956)	(1,387)
Amounts Recognized in the Consolidated Balance Sheets:
Other long-term assets		0	0
Accrued compensation and benefit costs		(26)	(24)
Pension and other benefit liabilities		(930)	(1,363)
Post-retirement medical benefits		0	0
Net Amounts Recognized		(956)	(1,387)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial loss		1,178	1,094
Prior service credit		(7)	(9)
Total Pre-tax Loss		1,171	1,085
Accumulated Benefit Obligation		4,179	4,161
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation - beginning		6,160	6,308
Service cost		29	31	32
Interest cost	[1]	158	195	203
Plan participants' contributions		4	4
Actuarial loss (gain)		(29)	636
Currency exchange rate changes		635	(774)
Plan Amendments/Curtailments		(4)	0
Benefits paid/settlements		(246)	(234)
Other		(4)	(6)
Benefit obligation - ending		6,703	6,160	6,308
Change in Plan Assets:
Fair value of plan assets -beginning		5,384	5,353
Actual return on plan assets		453	804
Employer contributions		161	154
Plan participants' contributions		4	4
Currency exchange rate changes		557	(694)
Benefits paid/settlements		(246)	(234)
Other		(5)	(3)
Fair Value of Plan Assets - ending		6,308	5,384	$ 5,353
Net Funded Status	[2]	(395)	(776)
Amounts Recognized in the Consolidated Balance Sheets:
Other long-term assets		193	17
Accrued compensation and benefit costs		(25)	(22)
Pension and other benefit liabilities		(563)	(771)
Post-retirement medical benefits		0	0
Net Amounts Recognized		(395)	(776)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial loss		1,562	1,741
Prior service credit		(28)	(28)
Total Pre-tax Loss		1,534	1,713
Accumulated Benefit Obligation		$ 6,483	$ 5,931

[1] Interest cost for Pension Benefits includes interest expense on non-TRA obligations of $257, $296 and $311 and interest expense (income) directly allocated to TRA participant accounts of $127, $83 and $(25) for the years ended December 31, 2017, 2016 and 2015, respectively.

[2] Includes under-funded and unfunded plans.