When editing your page type from the form view, the current document ID is correct. The editing "document ID" would be the ID you entered on that page type when creating it. For instance if you look at the Article page type, ArticleID is the primary key/ID. That is the physical ID of that record not the DocumentID.
To be clear, when adding/editing items in the content tree there are 3 different main objects:
- node (maintains hierarchy)
- document (contains overall page data, title, metadata, etc.)
- page type (content that gets displayed on a document)