Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Line Items]
Non-cancelable future minimum lease payments	$ 1,400
Rent expense under operating leases, including co-location arrangements	897	$ 734	$ 570
Other non-cancelable contractual obligations	2,500
Unused letters of credit	797
Property, Plant and Equipment | Construction in progress
Commitments and Contingencies Disclosure [Line Items]
Leases recorded on the balance sheet during the period	$ 940