Income Taxes Income Tax (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 14	$ 185	$ 191	$ 262
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	0	0	0
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	12	7	9
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(182)	(10)	(79)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	$ (1)	$ (3)	$ (1)