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Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2017 | Mar. 31, 2019 | Mar. 31, 2018
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 |  |  | 12,800 | 9,100
Intangibles not subject to amortization, Net Carrying Amount | 0 |  | 0 | 3,700
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 | 1,700 | $ 8,600 | 10,300 | 8,600
Intangibles not subject to amortization, Net Carrying Amount |  |  |  | 1,700
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 | 2,000 | $ 500 | 2,500 | 500
Intangibles not subject to amortization, Net Carrying Amount |  |  |  | 2,000
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 | 1,492 |  | 1,492 | 1,312
Intangibles subject to amortization, Impairment Loss |  |  | $ 1,208 |
Intangibles subject to amortization, Net Carrying Amount |  |  |  | $ 1,388
Intangibles not subject to amortization, Impairment Loss | $ 1,208 |  |  |

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