Acquisitions And Divestitures Acquisition of Unwired Holdings, Inc. (Details) - USD ($) $ in Millions	Oct. 01, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill		$ 1,508	$ 1,539	$ 656
Unwired Holdings, Inc.
Business Acquisition [Line Items]
Business Acquisition, Percentage of Equity Interests Acquired	100.00%
Purchase price, cash consideration	$ 191
Acquired cash excess net working capital and certain tax benefits	19
Total consideration transferred	210
Definite-lived intangible assets	63
Other assets purchased and liabilities assumed, net	17
Identifiable net assets acquired	80
Goodwill	130
Total purchase price allocation	$ 210
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years