Label

Element

Value

Prospectus [Line Items]

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Document Type

dei_DocumentType

497

Document Period End Date

dei_DocumentPeriodEndDate

Sep. 30, 2023

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

Jun. 18, 2024

Document Effective Date

dei_DocumentEffectiveDate

Jun. 18, 2024

First Trust Alerian Disruptive Technology Real Estate ETF

Prospectus [Line Items]

rr_ProspectusLineItems

Supplement to Prospectus [Text Block]

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Notwithstanding anything to the contrary in the Fund’s Prospectus or Summary Prospectus, the Average Annual Total Return table in the section entitled “Annual Total Return” is deleted in its entirety and replaced with the following:

Average Annual Total Returns for the Periods Ended December 31, 2023

	1 Year	5 Years	10 Years	Since Inception	Inception Date
Return Before Taxes	13.52%	3.39%	3.96%	2.39%	8/27/2007
Return After Taxes on Distributions	12.39%	2.27%	2.72%	1.11%
Return After Taxes on Distributions and Sale of Shares	7.96%	2.14%	2.53%	1.24%
Alerian Disruptive Technology Real Estate Index(1),(2) (reflects no deduction for fees, expenses or taxes)	13.46%	N/A	N/A	N/A
FTSE EPRA/NAREIT Developed Index (reflects no deduction for fees, expenses or taxes)	10.85%	3.79%	4.52%	3.09%
S&P Global REIT Index (reflects no deduction for fees, expenses or taxes)	10.23%	4.16%	4.72%	2.97%
MSCI World REIT Index (reflects no deduction for fees, expenses or taxes)	10.10%	5.79%	6.03%	3.31%
MSCI World Real Estate Index(2) (reflects no deduction for fees, expenses or taxes)	9.91%	4.35%	N/A	N/A
MSCI World Index (reflects no deduction for fees, expenses or taxes)	23.79%	12.80%	8.60%	6.52%

(1) On September 30, 2022, the Fund’s underlying index changed from the FTSE EPRA/NAREIT Developed Index to the Alerian Disruptive Technology Real Estate Index. Therefore, the Fund’s performance and historical returns shown for the periods prior to this date are not necessarily indicative of the performance that the Fund, based on its current index, would have generated.

(2) Performance data is not available for all the periods shown in the table for the index because performance data does not exist for some of the entire periods.