v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
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 Apr. 30, 2026
C000254671 [Member]  
Shareholder Report [Line Items]  
Fund Name iShares High Yield Muni Active ETF
Class Name iShares High Yield Muni Active ETF
Trading Symbol HIMU
Security Exchange Name CboeBZX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about iShares High Yield Muni Active ETF (the “Fund”) for the period of November 1, 2025 to April 30, 2026.
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 (800) 474‑2737.
Additional Information Phone Number (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 High Yield Muni Active ETF $27 0.53%(a)
​(a)
Annualized.
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.53% [1]
Net Assets $ 2,074,078,394
Holdings Count | Holding 839
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund statistics
Net Assets $2,074,078,394
Number of Portfolio Holdings 839
Portfolio Turnover Rate 35%
Holdings [Text Block]
What did the Fund invest in?
(as of April 30, 2026)
Sector allocation
Sector(a) Percent of Total
Investments(b)
County/City/Special District/School District 29.6 %
Health 17.6 %
Education 9.8 %
Housing 9.2 %
State 8.6 %
Transportation 7.7 %
Tobacco 6.9 %
Corporate 6.1 %
Utilities 4.4 %
Construction & Engineering 0.1 %
Ground Transportation — %(c)
Credit quality allocation
Credit Rating(d) Percent of Total
Investments(b)
AAA/Aaa 1.7 %
AA/Aa 13.2 %
A 5.0 %
BBB/Baa 5.3 %
BB/Ba 3.8 %
B 1.5 %
CCC/Caa 0.4 %
N/R 69.1 %
​(a)
For purposes of this report, sector sub-classifications may differ from those utilized by the Fund for compliance purposes.
​(b)
Excludes short-term securities.
​(c)
Rounds to less than 0.1%.
​(d)
For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.
Credit Quality Explanation [Text Block] For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.
Credit Ratings Selection [Text Block] For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc.
[1] Annualized.