Stockholders' Equity Tax Benefit (Expense) on Net Activity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax Benefit (Expense)	$ 4	$ 1	$ 3	$ 27
Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax Benefit (Expense)	0	0	(3)	4
Other Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax Benefit (Expense)	0	0	0	29
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax Benefit (Expense)	$ 4	$ 1	$ 6	$ (6)