Benefit Plans (Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Actuarial (gain) loss	$ 261	$ (187)
Amounts recognized on the Consolidated Balance Sheets as of December 31:
Other assets	2,285	2,025
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Balance at beginning of period	2,466	2,749
Service cost	0	0	$ 0
Interest cost	100	93	103
Participants' contributions	0	0
Actuarial (gain) loss	261	(187)
Benefits paid	(169)	(166)
Foreign currency translation and other	3	(7)
Settlements	0	(16)
Balance at end of period	2,661	2,466	2,749
Change in plan assets:
Balance beginning of period	2,025	2,261
Actual return on plan assets	292	(69)
Company contributions	134	23
Participants' contributions	0	0
Benefits paid	(169)	(166)
Foreign currency translation and other	3	(8)
Settlements	0	(16)
Balance end of period	2,285	2,025	2,261
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Funded status	(376)	(441)
Amounts recognized on the Consolidated Balance Sheets as of December 31:
Other assets	5	9
Other liabilities	(381)	(450)
Net amount recognized	(376)	(441)
Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit):
Prior service credit	0	0
Net actuarial (gain) loss	1,056	984
Net amount recognized	1,056	984
Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Balance at beginning of period	9	11
Service cost	0	0
Interest cost	0	0
Participants' contributions	4	3
Actuarial (gain) loss	1	0
Benefits paid	(6)	(5)
Foreign currency translation and other	0	0
Settlements	0	0
Balance at end of period	8	9	11
Change in plan assets:
Balance beginning of period	0	0
Actual return on plan assets	0	0
Company contributions	2	2
Participants' contributions	4	3
Benefits paid	(6)	(5)
Foreign currency translation and other	0	0
Settlements	0	0
Balance end of period	0	0	$ 0
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Funded status	(8)	(9)
Amounts recognized on the Consolidated Balance Sheets as of December 31:
Other assets	0	0
Other liabilities	(8)	(9)
Net amount recognized	(8)	(9)
Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit):
Prior service credit	0	0
Net actuarial (gain) loss	(2)	(3)
Net amount recognized	$ (2)	$ (3)