Income Taxes Uncertain tax positions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits	$ 38	$ 41	$ 40	$ 40
Tax positions taken in current year	1	1	0
Tax positions taken in prior years	0	1	1
Tax positions taken in current year	0	0	0
Tax positions taken in prior years	0	0	(1)
Settlements during the year	(4)	(1)	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	0	0	$ 0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	(33)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	37
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1
Unrecognized Tax Benefits	$ 2	$ 3