XML 80 R49.htm IDEA: XBRL DOCUMENT
v3.19.1

Recent accounting pronouncements Narrative (Details) - USD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Jan. 01, 2018 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of fair value measurement of equity [line items] |  |  |
Deficit |  | $ (547,839) | $ (610,908)
Accumulated other comprehensive income (loss) |  | (146,153) | (94,294)
Deferred tax expense (income) |  | $ (38,392) | $ 20,170
IFRS 9 | Increase (decrease) due to changes in accounting policy required by IFRSs |  |  |
Disclosure of fair value measurement of equity [line items] |  |  |
Deficit | $ 46,000 |  |
Accumulated other comprehensive income (loss) | (46,000) |  |
IFRS 9 | Long Term Investments | Increase (decrease) due to changes in accounting policy required by IFRSs |  |  |
Disclosure of fair value measurement of equity [line items] |  |  |
Deficit | 35,000 |  |
Accumulated other comprehensive income (loss) | (35,000) |  |
Deferred tax expense (income) | 1,000 |  |
IFRS 9 | Convertible senior subordinated notes | Increase (decrease) due to changes in accounting policy required by IFRSs |  |  |
Disclosure of fair value measurement of equity [line items] |  |  |
Deficit | 11,000 |  |
Accumulated other comprehensive income (loss) | $ (11,000) |  |

X
- Definition The amount of accumulated items of income and expense (including reclassification adjustments) that are not recognised in profit or loss as required or permitted by other IFRSs. [Refer: IFRSs [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_AccumulatedOtherComprehensiveIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of tax expense (income) relating to changes in deferred tax liabilities and deferred tax assets. [Refer: Deferred tax assets; Deferred tax liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph g -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_g_ii&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_DeferredTaxExpenseIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfFairValueMeasurementOfEquityLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A component of equity representing the entity's cumulative undistributed earnings or deficit. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 78 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_e&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph IG6 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_IG6&doctype=Implementation%20Guidance -URIDate 2017-03-09 + Details
Name: | ifrs-full_RetainedEarnings
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | ifrs-full_InitiallyAppliedIFRSsAxis=ifrs-full_InAccordanceWithIFRS9Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis=ifrs-full_IncreaseDecreaseDueToChangesInAccountingPolicyRequiredByIFRSsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialInstrumentsAxis=btg_LongTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialInstrumentsAxis=btg_ConvertibleSeniorSubordinatedNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |