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Consideration received by holders from principal amount of notes.

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Consideration received by holders from principal amount of per notes.

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Debt instrument maturity year.

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Debt instrument repurchase period.

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Percentage of currency devaluation.

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Percentage of foreign exchange loss recognized.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Fair value amount of debt instrument that was repurchased.

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The reporting currency-denominated expense (including losses) amount.

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Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

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The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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Subsequent Events - Additional Information (Detail)				2 Months Ended
Subsequent Events - Additional Information (Detail)	Mar. 07, 2018 USD ($) $ / shares	Feb. 02, 2018 USD ($)	Jul. 31, 2017 USD ($)	Feb. 28, 2018 USD ($) Kz / $	Dec. 31, 2017 Kz / $
Subsequent Event [Line Items]
Aggregate principal amount			$ 350,000,000
Debt instrument maturity year			2022
Offer \| Predecessor
Subsequent Event [Line Items]
Debt instrument repurchase period			60 days
Offer \| Minimum \| Predecessor
Subsequent Event [Line Items]
Net proceeds realized from asset sales exceed amount			$ 10,000,000
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 \| Kz / $					168
Devaluation Of Angolan kwanza Versus US Dollar \| Subsequent Event
Subsequent Event [Line Items]
Foreign currency exchange rate \| Kz / $				213
Percentage of devaluation of currency				27.00%
Estimated exchange loss				$ 14,000
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