XML 171 R159.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Subsequent Event - Additional Information (Detail) |  |  |  |  | 2 Months Ended | 4 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jul. 15, 2018 USD ($) shares | Mar. 07, 2018 USD ($) $ / shares | Feb. 02, 2018 USD ($) | Jul. 31, 2017 USD ($) | Feb. 28, 2018 USD ($) | Jul. 31, 2017 USD ($) | Jun. 30, 2018 USD ($) | Aug. 06, 2018 | Dec. 31, 2017
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  |  | $ 350,000,000 |  | $ 350,000,000 |  |  |
Debt instrument maturity year |  |  |  | 2022 |  |  |  |  |
Sonatide joint venture |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  | 49.00% |  | 49.00%
Tendered Notes |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 46,023 |  |  |  |  |  |  |
Offer | Predecessor |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Debt instrument repurchase period |  |  |  | 60 days |  | 60 days |  |  |
Offer | Minimum | Predecessor |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Net proceeds realized from asset sales exceed amount |  |  |  | $ 10,000,000 |  | $ 10,000,000 |  |  |
Offer | Senior Secured Notes |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Debt instrument fixed interest rate |  |  | 8.00% |  |  |  |  |  |
Debt instrument maturity year |  |  | 2022 |  |  |  |  |  |
Offer | Senior Secured Notes | Maximum |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  | $ 24,700,000 |  |  |  |  |  |
Subsequent Event |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Ownership percentage | 74.00% |  |  |  |  |  |  |  |
Fee payable on termination | $ 35,000,000 |  |  |  |  |  |  |  |
Subsequent Event | GulfMark |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Ownership percentage | 26.00% |  |  |  |  |  |  | 41.20% |
Fee payable on termination | $ 13,000,000 |  |  |  |  |  |  |  |
Shares received upon conversion | shares | 1.1 |  |  |  |  |  |  |  |
Shares received upon warrant coversion | shares | 1.1 |  |  |  |  |  |  |  |
Subsequent Event | Tendered Notes |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Aggregate principal amount |  | $ 46,023 |  |  |  |  |  |  |
Consideration received by holders from principal amount of per notes | $ / shares |  | $ 1.00 |  |  |  |  |  |  |
Consideration received by holders from principal amount of notes |  | $ 1.00 |  |  |  |  |  |  |
Cash equal to difference between offer amount and principal amount |  | $ 24,700,000 |  |  |  |  |  |  |
Subsequent Event | Offer | Senior Secured Notes |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Debt instrument fixed interest rate |  |  | 8.00% |  |  |  |  |  |
Debt instrument maturity year |  |  | 2022 |  |  |  |  |  |
Debt instrument maturity date |  |  | Mar. 06, 2018 |  |  |  |  |  |
Subsequent Event | Offer | Senior Secured Notes | Maximum |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  | $ 24,700,276 |  |  |  |  |  |
Devaluation Of Angolan kwanza Versus US Dollar |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Foreign currency exchange rate |  |  |  |  |  |  | 250 |  | 168
Percentage of devaluation of currency |  |  |  |  |  |  | 49.00% |  |
Estimated exchange loss |  |  |  |  |  |  | $ 20,600,000 |  |
Percentage of foreign exchange loss recognized |  |  |  |  |  |  | 49.00% |  |
Devaluation Of Angolan kwanza Versus US Dollar | Subsequent Event |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Foreign currency exchange rate |  |  |  |  | 213 |  |  |  |
Percentage of devaluation of currency |  |  |  |  | 27.00% |  |  |  |
Estimated exchange loss |  |  |  |  | $ 14,000,000 |  |  |  |
Percentage of foreign exchange loss recognized |  |  |  |  | 49.00% |  |  |  |
Devaluation Of Angolan kwanza Versus US Dollar | Subsequent Event | Sonatide joint venture |  |  |  |  |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |  |  |  |  |
Estimated exchange loss |  |  |  |  | $ 28,000,000 |  |  |  |

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