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Labor Union Contracts	6 Months Ended
Labor Union Contracts	Jun. 30, 2017
Labor Union Contracts [Abstract]
Concentration risk disclosure	Labor Union Contracts Approximately 10,000, or 45%, of our employees are members of various bargaining units represented by the Communication Workers of America ("CWA") and the International Brotherhood of Electrical Workers ("IBEW"). We recently reached new agreements with the CWA District 7 and IBEW Local 206 for the portion of these employees that were subject to collective bargaining agreements expiring on October 7, 2017. The new agreements were effective June 18, 2017 and will expire on March 28, 2020 and include terms substantially similar to those contained in the prior agreements.