v3.26.3
Investor A, C and Institutional [Member] N-1A Cover
May 31, 2026
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name BLACKROCK FUNDS II
Entity Central Index Key 0001398078
Entity Investment Company Type N-1A
Document Period End Date May 31, 2026
Prospectus Date Sep. 28, 2026