v3.25.4
S000051381 [Member] N-1A Cover
Oct. 31, 2025
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name AMG FUNDS IV
Entity Central Index Key 0000912036
Entity Investment Company Type N-1A
Document Period End Date Oct. 31, 2025
Prospectus Date Mar. 01, 2026