Annual report pursuant to Section 13 and 15(d)

Intangible Assets - Summary of Intangible Assets (Detail)

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Intangible Assets - Summary of Intangible Assets (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2014
Mar. 31, 2013
Schedule Of Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross Carrying Amount $ 2,870 $ 2,870
Finite-Lived Intangible Assets, Accumulated Amortization 762 582
Finite-Lived Intangible Assets, Net Carrying Amount 2,108 2,288
Indefinite Lived Intangible Assets, Gross Carrying Amount 12,800 12,800
Indefinite Lived Intangible Assets, Accumulated Amortization      
Indefinite Lived Intangible Assets, Net Carrying Amount 12,800 12,800
Backlog [Member]
    
Schedule Of Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross Carrying Amount 170 170
Finite-Lived Intangible Assets, Accumulated Amortization 170 170
Finite-Lived Intangible Assets, Net Carrying Amount      
Customer Relationships [Member]
    
Schedule Of Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross Carrying Amount 2,700 2,700
Finite-Lived Intangible Assets, Accumulated Amortization 592 412
Finite-Lived Intangible Assets, Net Carrying Amount 2,108 2,288
Nuclear Permits [Member]
    
Schedule Of Intangible Assets [Line Items]    
Indefinite Lived Intangible Assets, Gross Carrying Amount 10,300 10,300
Indefinite Lived Intangible Assets, Accumulated Amortization      
Indefinite Lived Intangible Assets, Net Carrying Amount 10,300 10,300
Trade name [Member]
    
Schedule Of Intangible Assets [Line Items]    
Indefinite Lived Intangible Assets, Gross Carrying Amount 2,500 2,500
Indefinite Lived Intangible Assets, Accumulated Amortization      
Indefinite Lived Intangible Assets, Net Carrying Amount $ 2,500 $ 2,500