v3.26.1
Vanguard Balanced Index Fund N-1A Cover
Dec. 31, 2025
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name VANGUARD VALLEY FORGE FUNDS
Entity Central Index Key 0000889519
Entity Investment Company Type N-1A
Document Period End Date Dec. 31, 2025
Prospectus Date Apr. 28, 2026