Pension and Postretirement Benefit Plans - Reconciliation of Level 3 Pension Plan Assets (Details) - Pension Plan [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at beginning of period		$ 1,584
Fair value at end of period		1,372		$ 1,584
Insurance Contracts [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at beginning of period	[1]	33
Fair value at end of period	[1]	35		33
Foreign Plan [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at beginning of period		71		51
Fair value at end of period		71		71
Foreign Plan [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at beginning of period		33
Fair value at end of period		35		33
Foreign Plan [Member] | Insurance Contracts [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Actual gains relating to assets still held at the reporting date		4		3
Purchases, sales and settlements		(1)		1
Currency impact		(1)		3
Transfers into (out of) Level 3
Foreign Plan [Member] | Insurance Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at beginning of period		33	[1]	16
Transfers into (out of) Level 3				10
Fair value at end of period	[1]	$ 35		$ 33

[1] This category comprises contracts placed with insurance companies where the underlying assets are invested in fixed interest securities.