Aggregate amount for legal actions for which no loss amount has been accrued.

No definition available.

Name:	meli_AggregateAmountForLegalActionsForWhichNoLossAmountHasBeenAccrued
Namespace Prefix:	meli_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Loss contingency deposits with court of law.

+ References

No definition available.

+ Details

Name:	meli_LossContingencyDepositsWithCourtOfLaw
Namespace Prefix:	meli_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Product Liability, Contingency, Recorded Allowance

+ References

No definition available.

+ Details

Name:	meli_ProductLiabilityContingencyRecordedAllowance
Namespace Prefix:	meli_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Estimated amount of loss resulting from an adverse tax position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

Name:	us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

+ References

+ Details

Name:	us-gaap_LossContingencyAccrualProvision
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Present value of the accrual for product liability loss contingencies as of the balance sheet date (if the accrual qualifies for discounting).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q1)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

+ Details

Name:	us-gaap_ProductLiabilityContingencyAccrualPresentValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=meli_CityOfSaoPauloTaxClaimMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=meli_BuyerProtectionProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Narrative I) (Details) $ in Thousands, R$ in Millions		9 Months Ended	12 Months Ended
	Aug. 15, 2011 BRL (R$)	Sep. 30, 2018 USD ($)	Dec. 31, 2007 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Reserves for proceeding-related contingencies		$ 5,440
Aggregate amount for legal actions for which no loss amount has been accrued		6,845
Loss accrued for reasonably possible legal actions		0
City of Sao Paulo Tax Claim [Member]
Loss Contingencies [Line Items]
Reserves for proceeding-related contingencies		3,900
Approximate additional amount related to asserted taxes and fines			$ 5,900
Deposit with court \| R$	R$ 9.5
Buyer Protection Program [Member]
Loss Contingencies [Line Items]
Maximum potential exposure		633,660		$ 925,690
Product liability, contingency, recorded allowance		$ 5,085		$ 1,087