Pension and Other Postretirement Benefits - Change in Plan Assets and Reconciliation of Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Accrued expenses	$ (14)	$ (16)
Pension
Change in plan assets:
Fair value of plan assets at January 1	2,550	2,832
Actual return on plan assets	379	(82)
Company contributions	27	23
Plan participants’ contributions	2	2
Benefits paid	(156)	(165)
Foreign currency translation	42	(60)
Fair value of plan assets at December 31	2,844	2,550
Funded status
Funded status	113	121
Other immaterial plans	(42)	(46)
Net asset (liability) at December 31	71	75
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Net asset (liability) at end of year	71	75
The pre-tax amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	568	552
Prior service cost	7	8
Pre-tax net actuarial (gain) loss and prior service cost	575	560
Accumulated benefit obligation	2,589	2,299
Plans with accumulated benefit obligation in excess of plan assets as of December 31:
Projected benefit obligation	194	176
Accumulated benefit obligation	188	170
Fair value of plan assets	29	28
Other Postretirement Benefits
Change in plan assets:
Fair value of plan assets at January 1	333	373
Actual return on plan assets	66	(19)
Company contributions	5	7
Plan participants’ contributions	12	12
Benefits paid	(42)	(40)
Foreign currency translation	0	0
Fair value of plan assets at December 31	374	333
Funded status
Funded status	(196)	(178)
Other immaterial plans	(5)	(5)
Net asset (liability) at December 31	(201)	(183)
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Net asset (liability) at end of year	(201)	(183)
The pre-tax amounts recognized in accumulated other comprehensive income consist of:
Net actuarial (gain) loss	(35)	(53)
Prior service cost	0	0
Pre-tax net actuarial (gain) loss and prior service cost	(35)	(53)
Other assets | Pension
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Other assets	297	290
Other assets | Other Postretirement Benefits
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Other assets	0	0
Accrued expenses | Pension
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Accrued expenses	(11)	(12)
Accrued expenses | Other Postretirement Benefits
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Accrued expenses	(3)	(4)
Other noncurrent liabilities | Pension
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Other noncurrent liabilities	(215)	(203)
Other noncurrent liabilities | Other Postretirement Benefits
The amounts recognized in the Statement of Financial Position as of December 31 consist of:
Other noncurrent liabilities	$ (198)	$ (179)