Class K [Member] Expense Example - Class K - BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO - Class K	May 31, 2026 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 75
Expense Example, with Redemption, 3 Years	233
Expense Example, with Redemption, 5 Years	406
Expense Example, with Redemption, 10 Years	$ 906

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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