v3.25.1
Shareholder Report
 6 Months Ended
Jan. 31, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name BlackRock ETF Trust II
Entity Central Index Key 0001804196
Entity Investment Company Type N-1A
Document Period End Date Jan. 31, 2025
C000243161 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares Large Cap Moderate Buffer ETF
Class Name iShares Large Cap Moderate Buffer ETF
Trading Symbol IVVM
Security Exchange Name CboeBZX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares Large Cap Moderate Buffer ETF (the “Fund”) for the period of August 1, 2024 to January 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at 1‑800‑iShares (1‑800‑474‑2737).
Additional Information Phone Number 1‑800‑iShares (1‑800‑474‑2737)
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares Large Cap Moderate Buffer ETF $25(a) 0.48%(a)(b)
​(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
​(b)
Annualized.
Expenses Paid, Amount $ 25 [1]
Expense Ratio, Percent 0.48% [1],[2]
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Average Annual Return [Table Text Block]
Average annual total returns
6-Month
Total
Returns		 1 Year Since Fund
Inception
Fund NAV 7.90 % 17.00 % 15.27 %
S&P 500® Index 10.12 26.38 24.24
Performance Inception Date Jun. 28, 2023
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 89,868,544
Holdings Count | Holding 6
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $89,868,544
Number of Portfolio Holdings 6
Portfolio Turnover Rate 0%
Holdings [Text Block]
What did the Fund invest in?
(as of January 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 100.2 %
Purchased Put Options 1.2 %
Futures (0.0 )%(a)
Written Put Options (0.5 )%
Written Call Options (1.3 )%
Money Market Funds 0.4 %
Other assets, less liabilities 0.0
​(b)
​(a)
Rounds to greater than (0.1)%.
​(b)
Rounds to less than 0.1%.
C000243162 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares Large Cap Deep Buffer ETF
Class Name iShares Large Cap Deep Buffer ETF
Trading Symbol IVVB
Security Exchange Name CboeBZX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares Large Cap Deep Buffer ETF (the “Fund”) for the period of August 1, 2024 to January 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at 1‑800‑iShares (1‑800‑474‑2737).
Additional Information Phone Number 1‑800‑iShares (1‑800‑474‑2737)
Additional Information Website blackrock.com/fundreports
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Fund name Costs of a $10,000
investment		 Costs paid as a percentage of a
$10,000 investment
iShares Large Cap Deep Buffer ETF $26(a) 0.49%(a)(b)
​(a)
Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
​(b)
Annualized.
Expenses Paid, Amount $ 26 [3]
Expense Ratio, Percent 0.49% [3],[4]
Performance Past Does Not Indicate Future [Text] Past performance is not an indication of future results.
Average Annual Return [Table Text Block]
Average annual total returns
6-Month
Total
Returns		 1 Year Since Fund
Inception
Fund NAV 8.35 % 19.35 % 15.20 %
S&P 500® Index 10.12 26.38 24.24
Performance Inception Date Jun. 28, 2023
No Deduction of Taxes [Text Block] Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Updated Performance Information Location [Text Block] Visit blackrock.com for more recent performance information.
Net Assets $ 82,087,964
Holdings Count | Holding 6
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $82,087,964
Number of Portfolio Holdings 6
Portfolio Turnover Rate 0%
Holdings [Text Block]
What did the Fund invest in?
(as of January 31, 2025)
Portfolio composition
Asset Type Percent of
Net Assets
Equity Funds 100.2 %
Purchased Put Options 0.6 %
Futures (0.0 )%(a)
Written Put Options (0.1 )%
Written Call Options (1.1 )%
Money Market Funds 0.4 %
Liabilities in Excess of Other Assets (0.0 )(a)
​(a)
Rounds to greater than (0.1)%.
[1] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[2] Annualized.
[3] Excludes fees and expenses incurred indirectly as a result of investments in underlying funds.
[4] Annualized.