Acquisitions, Dispositions And Other Adjustments (Other Events) (Narrative) (Details)	6 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Governmental Contracts Subject to Renegotiation [Abstract]
Refunds Due under Government Contracts Not Reasonably Estimable	success-based payments of $6,500 over the next five years
Basis of Provision for Refunds under Government Contracts	On March 30, 2017, the First Responder Network Authority (FirstNet) announced its selection of AT&T to build and manage the first nationwide broadband network dedicated to America’s first responders. FirstNet expects to provide 20 MHz of valuable telecommunications spectrum and success-based payments of $6,500 over the next five years to support network buildout. The actual reach of the network and our investment over the 25-year period will be determined by the number of individual states electing to participate in FirstNet. We do not expect FirstNet to materially impact our 2017 results.
Number of states opted-in to the FirstNet program		7