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Labor Union Contracts	3 Months Ended
Labor Union Contracts	Mar. 31, 2019
Risks and Uncertainties [Abstract]
Labor Union Contracts	Labor Union Contracts As of March 31, 2019, approximately 44% of our employees were members of various bargaining units represented by the Communication Workers of America and the International Brotherhood of Electrical Workers. We believe that relations with our employees continue to be generally good.