Other Postretirement Employee Benefit Plans Other Postretirement Employee Benefit Plans (Disaggregation of Service Cost) (Details) - Other postretirement benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ (1)
Other income (expense), net	(3)	(3)	(2)
Total	(3)	(3)	(3)
Cost of sales
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Selling, general and administrative expenses
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ (1)