Pension and Other Benefit Programs - Benefit Obligations and Fair Value of Plan Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$ 791,000,000	$ 875,000,000
Interest cost	28,000,000	26,000,000	$ 27,000,000
Actuarial (gain) loss	90,000,000	(61,000,000)
Benefits paid	(48,000,000)	(49,000,000)
Benefit obligation at year end	861,000,000	791,000,000	875,000,000
Change in plan assets:
Fair value of plan assets at beginning of year	794,000,000	869,000,000
Actual return on plan assets	148,000,000	(26,000,000)
Contributions	0	0	136,000,000
Benefits paid	(48,000,000)	(49,000,000)
Fair value of plan assets at end of year	894,000,000	794,000,000	$ 869,000,000
Funded status	33,000,000	3,000,000
Accumulated benefit obligation	861,000,000	791,000,000
Accrued pension plan asset
Amounts recognized in the accompanying consolidated balance sheets:
Accrued pension plan asset	$ 33,000,000	$ 3,000,000