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Intangible Assets - Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2014 | Mar. 31, 2013
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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

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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph ((a)(1),(b)) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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