Quarterly report pursuant to Section 13 or 15(d)

Intangible Assets - Summary of Intangible Assets (Detail)

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Intangible Assets - Summary of Intangible Assets (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Dec. 31, 2017
Dec. 31, 2017
Mar. 31, 2017
Schedule Of Intangible Assets [Line Items]      
Intangibles not subject to amortization, Gross Carrying Amount $ 12,800 $ 12,800 $ 12,800
Intangibles not subject to amortization, Impairment Loss   9,100  
Intangibles not subject to amortization, Net Carrying Amount 3,700 3,700 12,800
Permits [Member]      
Schedule Of Intangible Assets [Line Items]      
Intangibles not subject to amortization, Gross Carrying Amount 10,300 10,300 10,300
Intangibles not subject to amortization, Impairment Loss 8,600 8,600  
Intangibles not subject to amortization, Net Carrying Amount 1,700 1,700 10,300
Tradename [Member]      
Schedule Of Intangible Assets [Line Items]      
Intangibles not subject to amortization, Gross Carrying Amount 2,500 2,500 2,500
Intangibles not subject to amortization, Impairment Loss 500 500  
Intangibles not subject to amortization, Net Carrying Amount 2,000 2,000 2,500
Customer Relationships [Member]      
Schedule Of Intangible Assets [Line Items]      
Intangibles subject to amortization, Gross Carrying Amount 2,700 2,700 2,700
Intangibles subject to amortization, Accumulated Amortization 1,267 1,267 1,132
Intangibles subject to amortization, Net Carrying Amount $ 1,433 $ 1,433 $ 1,568