Financial instruments (Details 26) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	$ (5,466)	$ (439)	$ 8,913
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	11,412	6,018	10,190
Gain (loss) recognized on derivatives (ineffective portion)	268	(1,352)	(145)
Net Investment Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	(277)	0	(901)
Interest rate swaps [member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	(834)	627	35
Interest rate swaps [member] \| Gain loss on interest rate swap [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	0	0	0
Gain (loss) recognized on derivatives (ineffective portion)	242	(1,258)	(229)
Cross-currency swaps [member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	(1,924)	(1,299)	5,367
Cross-currency swaps [member] \| Gain loss on foreign exchange [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	0	0	0
Gain (loss) recognized on derivatives (ineffective portion)	26	16	84
Cross-currency swaps [member] \| Interest income - loans [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	7,611	0	0
Gain (loss) recognized on derivatives (ineffective portion)	0	(110)	0
Forward foreign exchange [member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	(2,708)	233	3,511
Forward foreign exchange [member] \| Net Investment Hedging [Member]
Disclosure of financial instruments [Line Items]
Gains (loss) recognized in OCI (effective portion)	(277)	0	(901)
Forward foreign exchange [member] \| Interest income - loans [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	3,991	(4,751)	(1,821)
Gain (loss) recognized on derivatives (ineffective portion)	0	0	0
Forward foreign exchange [member] \| Interest income - securities at FVOCI [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	0	0	(694)
Gain (loss) recognized on derivatives (ineffective portion)	0	0	0
Forward foreign exchange [member] \| Interest expense - borrowings and debt [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	0	0	0
Gain (loss) recognized on derivatives (ineffective portion)	0	0	0
Forward foreign exchange [member] \| Interest expenses - deposits [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	(190)	1,672	166
Gain (loss) recognized on derivatives (ineffective portion)	0	0	0
Forward foreign exchange [member] \| Gain loss on foreign currency exchange [Member] \| Cash Flow Hedging [Member]
Disclosure of financial instruments [Line Items]
Gain (loss) reclassified from accumulated OCI to the consolidated statement of profit or loss	0	9,097	12,539
Gain (loss) recognized on derivatives (ineffective portion)	$ 0	$ 0	$ 0

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.

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The gain (loss) on hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24C
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24C_a_i&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_GainLossOnHedgeIneffectiveness
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gains (losses) recognised in other comprehensive income on hedges of net investments in foreign operations, net of tax. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 39
-IssueDate 2017-01-01
-Paragraph 102
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=39&date=2017-03-01&anchor=para_102_a&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 91
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_a&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24C
-Subparagraph b
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24C_b_i&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24E
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24E_a&doctype=Standard
-URIDate 2017-03-09

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 9
-IssueDate 2017-01-01
-Paragraph 6.5.13
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=9&date=2017-03-01&anchor=para_6.5.13_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_GainsLossesOnHedgesOfNetInvestmentsInForeignOperationsNetOfTax
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of other comprehensive income that will be reclassified to profit or loss, net of tax. [Refer: Other comprehensive income]

+ References

Reference 1: 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

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 82A
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_82A&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_OtherComprehensiveIncomeThatWillBeReclassifiedToProfitOrLossNetOfTax
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_NetInvestmentHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_InterestRateSwapContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_GainlossOnInterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=blx_CrosscurrencyInterestRateSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_GainlossOnForeignExchangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_InterestIncomeLoansAtAmortizedCostMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=blx_ForeignForwardContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_InterestIncomeSecuritiesAtFVOCIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_InterestExpenseBorrowingsAndDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_InterestExpensesDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	blx_InterestIncomeStatementsAxis=blx_GainlossOnForeignCurrencyExchangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: