Income Taxes Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in Unrecognized Tax Benefits [Line Items]
Unrecognized Tax Benefits	$ 111	$ 100	$ 210
Federal and State [Member]
Changes in Unrecognized Tax Benefits [Line Items]
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	18	4
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(4)	(4)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	13	10
Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities	(16)	(119)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	$ 0	$ (1)