Pension and Other Benefit Programs - Benefit Obligation, Benefits Paid During the Period, Accrued Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$ 861	$ 791	$ 875
Interest cost	28	26	$ 27
Actuarial (gain) loss	90	(61)
Benefits paid	(48)	(49)
Amounts recognized in the accompanying consolidated balance sheets:
Accrued employee benefits	(198)	(204)
Post-retirement Benefit Plans
Change in benefit obligation:
Benefit obligation at beginning of year	142	154
Interest cost	5	5
Actuarial (gain) loss	(8)	(19)
Employee contributions	3	3
Benefits paid	(12)	(13)
Amounts recognized in the accompanying consolidated balance sheets:
Other current liabilities	(8)	(10)
Accrued employee benefits	$ (134)	$ (144)