Class K Shares [Member] Expense Example - Class K - BLACKROCK LIFEPATH INDEX RETIREMENT FUND - Class K Shares	Dec. 31, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 9
Expense Example, with Redemption, 3 Years	33
Expense Example, with Redemption, 5 Years	60
Expense Example, with Redemption, 10 Years	$ 139

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