Income Taxes Accounting for Uncertainty in Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits balance	$ 33	$ 34	$ 34	$ 52
Addition based on tax positions related to the current year	2	0	0
Increase for tax positions of prior years	0	6	0
Decrease for tax positions of prior years	0	0	(3)
Decrease for statute of limitation expiration	$ (3)	$ (6)	$ (15)