v3.25.2
Investor A C and Institutional [Member] N-1A Cover
May 31, 2025
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name BLACKROCK CALIFORNIA MUNICIPAL SERIES TRUST
Entity Central Index Key 0000765199
Entity Investment Company Type N-1A
Document Period End Date May 31, 2025
Prospectus Date Sep. 25, 2025