Description

From the docs:
"The _id field may contain values of any BSON data type, other than an array."

https://docs.mongodb.com/manual/core/document/#the-_id-field

However, regexes and undefined are also disallowed as values for _id. The docs should be updated to reflect this restriction. Code:
https://github.com/mongodb/mongo/blob/cf55779be0b1ed2f12c71e13e634b81007094777/src/mongo/db/ops/insert.cpp#L137-L144

Scope of changes

Impact to Other Docs

MVP (Work and Date)

Resources (Scope or Design Docs, Invision, etc.)