Income Taxes Schedule of Unrecognized Tax Benefits Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 195	$ 235	$ 289	$ 296
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	28	23	64
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	9	35	12
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	5	2	31
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	46	24	60
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	7	9	19
Unrecognized Tax Benefits, Increase (Decrease) Resulting from Foreign Currency Translation	$ (11)	$ (11)	$ (11)