In terms of legal account documents - No one does physical paper as system of record anymore (it's all digitized), so survival of the documentation would rely solely on institution-specific IT policies.
If your bank hides tapes in mountains, most critical legal documents are probably going to survive. Not sure what regulations say about requirements here.
The general ledger as well as ledgers for all customer accounts are less likely to survive. Many days of transactions would be lost in the best case (e.g. PDC+DR nuked and most recent offsite is "only" 12 days old as of the attack).