Quarterly report pursuant to Section 13 or 15(d)

Contract Costs - Additional Information (Detail)

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Contract Costs - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Project
Sep. 30, 2011
Project
Long-term Contracts or Programs Disclosure [Line Items]        
Percentage of pass-through costs included in revenue 58.20% 46.90% 46.00% 46.60%
Total revenue recorded in relation to orders change in projects     $ 1.7 $ 1.7
Number of projects orders changed     2 2
Total revenue recorded in relation to re-measure units and quantities within customer construction contract     6.6  
Recognized contract losses from uncompleted contracts (20.6) (1.8) (21.2) (2.4)
Unfavorable reduction in gross margin due to contract loss from uncompleted contracts $ 26.8 $ 1.8 $ 24.5 $ 2.4