Shareholder Report |
6 Months Ended | |||||||||||
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Mar. 31, 2026
USD ($)
Holding
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| 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 | Mar. 31, 2026 | |||||||||||
| C000262359 | ||||||||||||
| Shareholder Report [Line Items] | ||||||||||||
| Fund Name | iShares Mortgage-Backed Securities Active ETF | |||||||||||
| Trading Symbol | MBBA | |||||||||||
| Security Exchange Name | CboeBZX | |||||||||||
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about iShares Mortgage-Backed Securities Active ETF (the “Fund”) for the period of October 1, 2025 to March 31, 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. Effective as of the close of trading on the New York Stock Exchange on January 23, 2026, BlackRock Mortgage-Backed Securities Fund was reorganized into the Fund. | |||||||||||
| Material Fund Change Notice [Text Block] | ||||||||||||
| 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)
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| Expenses Paid, Amount | $ 24 | |||||||||||
| Expense Ratio, Percent | 0.48% | [1] | ||||||||||
| AssetsNet | $ 125,783,910 | |||||||||||
| Holdings Count | Holding | 531 | |||||||||||
| InvestmentCompanyPortfolioTurnover | 1127.00% | |||||||||||
| Additional Fund Statistics [Text Block] | Key Fund statistics
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- Details
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