Pension and Other Benefit Programs - Components of Pension Plan Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Interest cost	$ 28	$ 26	$ 27
Estimated return on plan assets	(31)	(29)	(44)
Amortization of loss	3	4	2
Aggregate pension expense (benefit)	$ 0	$ 1	$ (15)