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Income Taxes - Additional Information (Detail) - USD ($) | 1 Months Ended | 5 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jul. 31, 2017 | Dec. 31, 2017 | Jun. 30, 2018 | Dec. 31, 2018 | Mar. 31, 2017
Income Tax [Line Items] |  |  |  |  |
Federal statutory tax rate |  | 35.00% | 21.00% |  |
Cancellation of indebtedness (COD) income | $ 853,000,000 |  |  |  |
Total amount of reduction of tax attributes | 806,000,000 |  |  |  |
Net operating losses and depreciable assets | 518,000,000 |  |  |  |
Attribute reduction in stock of foreign subsidiaries | 288,000,000 |  |  |  |
Excess COD income attributed to subsidiaries | 37,000,000 |  |  |  |
Deferred tax recognized on excess COD income | 10,000,000 |  |  |  |
Reduced in net operating loss carryforwards |  | $ 201,100,000 |  |  |
Valuation allowance |  | 43,218,000 | $ 47,700,000 |  | $ 2,300,000
Unrecognized deferred tax liability for temporary differences related to investments in foreign subsidiaries estimated amount |  | 4,000,000 |  |  |
Income tax penalties and interest |  | 9,800,000 |  |  |
Net impact in income loss |  | 0 | 0 |  |
Reduction in net deferred tax asset |  | 27,300,000 |  |  |
Recognized provisional deemed dividend |  | 43,200,000 |  |  |
Net deferred tax assets |  | 43,200,000 | 47,700,000 |  |
Adjustments to provisional amounts recorded |  |  | 0 |  |
One-time transition tax, adjustments to provisional amounts recorded |  |  | 0 |  |
Tax act, executive compensation, cap on deductibility, amount |  |  | $ 1,000,000 |  |
Tax act, interest expense limitation, minimum percentage of adjusted taxable income |  |  | 30.00% |  |
Estimate of interest expense limitation before consideration of valuation allowance |  |  | $ 7,500,000 |  |
Scenario Plan |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Federal statutory tax rate |  |  |  | 21.00% |
Federal NOL |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Net operating loss ("NOL") carryforwards |  | 215,600,000 |  |  | 47,600,000
Foreign NOL |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Tax credit |  | $ 2,300,000 |  |  | $ 2,300,000
Tax credit year expire, start year |  | 2026 |  |  |
Tax credit year expire, end year |  | 2027 |  |  |
Domestic Subsidiaries |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Excess COD income attributed to subsidiaries | 47,000,000 |  |  |  |
Deferred tax recognized on excess COD income | $ 0 |  |  |  |
Intercompany Vessel Sales |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Remaining unamortized amount |  | $ 0 |  |  |

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