Annual report pursuant to Section 13 and 15(d)

Goodwill and Other Intangible Assets - Summary of Changes in Quanta's Goodwill (Detail)

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Goodwill and Other Intangible Assets - Summary of Changes in Quanta's Goodwill (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Goodwill [Line Items]      
Goodwill acquired during the period $ 64,779 $ 43,758  
Foreign currency translation related to goodwill 2,055 (3,642)  
Purchase price adjustments related to prior periods   (61)  
Goodwill 1,537,645 1,470,811 1,430,756
Electric Power Division [Member]
     
Goodwill [Line Items]      
Goodwill acquired during the period 57,451 34,900  
Foreign currency translation related to goodwill 2,087 (3,564)  
Operating unit reorganization 16,912 216,090  
Goodwill 1,065,152 988,702 741,276
Natural Gas and Pipeline Division [Member]
     
Goodwill [Line Items]      
Goodwill acquired during the period 7,328 8,858  
Foreign currency translation related to goodwill (32) (78)  
Operating unit reorganization 16,809 (216,090)  
Purchase price adjustments related to prior periods   (61)  
Goodwill 137,703 113,598 320,969
Fiber Optic Licensing [Member]
     
Goodwill [Line Items]      
Operating unit reorganization (33,721)    
Goodwill $ 334,790 $ 368,511 $ 368,511