Employee Benefit Plans - Accumulated Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		$ 9,141	$ 9,350
Accumulated Benefit Obligation		8,965	9,183
Fair value of plan assets		6,968	7,106
United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		4,161	4,126
Accumulated Benefit Obligation		4,161	4,126
Fair value of plan assets		2,774	2,806
Defined Benefit Plan, Fair Value of Plan Assets		2,774	2,806	$ 3,081
Pension Benefit Obligation		4,161	4,126	4,642
Net Funded Status	[1]	(1,387)	(1,320)
Foreign Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		4,980	5,224
Accumulated Benefit Obligation		4,804	5,057
Fair value of plan assets		4,194	4,300
Defined Benefit Plan, Fair Value of Plan Assets		5,384	5,353	5,930
Pension Benefit Obligation		6,160	6,308	$ 6,962
Net Funded Status	[1]	(776)	(955)
Underfunded [Member] | United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		3,820	3,781
Accumulated Benefit Obligation		3,820	3,781
Fair value of plan assets		2,774	2,806
Underfunded [Member] | Foreign Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		4,535	4,803
Accumulated Benefit Obligation		4,368	4,644
Fair value of plan assets		4,194	4,300
Unfunded [Member] | United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		341	345
Accumulated Benefit Obligation		341	345
Fair value of plan assets		0	0
Defined Benefit Plan, Fair Value of Plan Assets		0
Pension Benefit Obligation		341
Net Funded Status		(341)
Unfunded [Member] | Foreign Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		445	421
Accumulated Benefit Obligation		436	413
Fair value of plan assets		0	$ 0
Funded [Member] | United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		2,774
Pension Benefit Obligation		3,820
Net Funded Status		(1,046)
UNITED KINGDOM | Defined Benefit Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		3,445
Pension Benefit Obligation		3,679
Net Funded Status		(234)
Canada | Defined Benefit Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		661
Pension Benefit Obligation		700
Net Funded Status		(39)
Pension Plans All Other Countries [Member] | Defined Benefit Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,278
Pension Benefit Obligation		1,781
Net Funded Status		(503)
Funded and Unfunded Plans [Member] | Foreign Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		8,158
Pension Benefit Obligation		10,321
Net Funded Status		$ (2,163)

[1] Includes under-funded and un-funded plans.