Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

497

Document Period End Date

dei_DocumentPeriodEndDate

Sep. 30, 2024

Entity Registrant Name

dei_EntityRegistrantName

First Trust Exchange-Traded Fund II

Entity Central Index Key

dei_EntityCentralIndexKey

0001364608

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Mar. 17, 2025

Document Effective Date

dei_DocumentEffectiveDate

Mar. 17, 2025

First Trust Dow Jones International Internet ETF

Prospectus [Line Items]

rr_ProspectusLineItems

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

Notwithstanding anything to the contrary in the Fund’s Prospectus or Summary Prospectus, effective March 24, 2025, the fifth sentence of the third paragraph under the section entitled “Principal Investment Strategies” is hereby deleted in its entirety and replaced with the following:

“However, the weight for a single company is capped at 10% and the cumulative weight of all companies with weights greater than 4.5% is capped at 45%.”