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Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands | Mar. 31, 2017 | Mar. 31, 2016
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Schedule Of Intangible Assets [Line Items] |  |
Indefinite Lived Intangible Assets, Gross Carrying Amount | $ 12,800 | $ 12,800
Indefinite Lived Intangible Assets, Net Carrying Amount | 12,800 | 12,800
Permits [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Indefinite Lived Intangible Assets, Gross Carrying Amount | 10,300 | 10,300
Indefinite Lived Intangible Assets, Net Carrying Amount | 10,300 | 10,300
Tradename [Member] |  |
Schedule Of Intangible Assets [Line Items] |  |
Indefinite Lived Intangible Assets, Gross Carrying Amount | 2,500 | 2,500
Indefinite Lived Intangible Assets, Net Carrying Amount | 2,500 | 2,500
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 | 1,132 | 952
Finite-Lived Intangible Assets, Net Carrying Amount | $ 1,568 | $ 1,748

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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=66006027&loc=d3e16323-109275 + Details
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