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Segment Information - Additional Information (Detail)
3 Months Ended
Mar. 31, 2013
Customer
Segment
Mar. 31, 2012
Customer
Segment Reporting Information [Line Items]    
Number of reportable segments 2  
Number of customers individually accounting for more than ten percent of total operating revenues 0 0
Percentage maximum accounted for 10.00% 10.00%
Wireline
   
Segment Reporting Information [Line Items]    
Number of countries outside the United States of America to which our Wireline segment provides products and services 150