Schedule I - Condensed Financial Information Of Parent Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	$ 90	$ 70	$ 44
Charitable donations	(12)	(33)	(8)
Total other income (expense), net	130	102	86
Parent Company
Other Nonoperating Income (Expense) [Line Items]
Non-service cost components of net periodic benefit income	2	2	2
Charitable donations	(3)	(13)	0
Other expenses, net	(1)	(1)	0
Total other income (expense), net	$ (2)	$ (12)	$ 2