| Contract Costs - Additional Information (Detail) (USD $) | 3 Months Ended | ||
|---|---|---|---|
| Mar. 31, 2014
 Project | Mar. 31, 2013
 Project | Dec. 31, 2013 | |
| Long-term Contracts or Programs Disclosure [Line Items] | |||
| Pass-through costs as a percentage of revenue | 68.90% | 56.30% | |
| Costs and estimated earnings in excess of billings on uncompleted contracts, unbilled costs | $ 20,692,000 | $ 24,727,000 | |
| Billings in excess of costs and estimated earnings, advances | 28,617,000 | 35,006,000 | |
| Total revenue recorded in relation to orders change in projects | 5,000,000 | 4,800,000 | |
| Number of projects orders changed | 7 | 3 | |
| Unbilled Contract Costs [Member] | |||
| Long-term Contracts or Programs Disclosure [Line Items] | |||
| Costs and estimated earnings in excess of billings on uncompleted contracts, unbilled costs | 14,300,000 | ||
| Number of major customers | 2 | ||
| Contract Advances [Member] | |||
| Long-term Contracts or Programs Disclosure [Line Items] | |||
| Number of major customers | 3 | ||
| Billings in excess of costs and estimated earnings, advances | $ 20,900,000 | ||