Income Taxes Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in Unrecognized Tax Benefits [Line Items]
Unrecognized Tax Benefits	$ 145	$ 141	$ 111
Federal and State [Member]
Changes in Unrecognized Tax Benefits [Line Items]
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	2	22
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(6)	(5)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	20	13
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(2)	0
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	$ (10)	$ 0