Stockholders' Equity Tax Benefit (Expense) on Net Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Loss, Tax Expense	$ (10)	$ (6)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Loss, Tax Expense	(3)	(4)
Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Loss, Tax Expense	$ (7)	$ (2)