Income Taxes (Details 4) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Tax Credit Carryforward, Valuation Allowance	$ 111	$ 189
Unrecognized Tax Benefits That Would Not Impact Effective Tax Rate	10
Continuing Operations [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Accrued interest and penalties	12	14
Unrecognized Tax Benefits	113	$ 100	$ 91
U.S. state [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Tax Credit Carryforward, Valuation Allowance	100
Internal Revenue Service (IRS) [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Tax Credit Carryforward, Valuation Allowance	300
Timing of Anticipated Impact [Domain] | Continuing Operations [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits	$ 22