You would need OCR (Optical Character Recognition) software to convert the
scanned document to recognizable values. Even with good OCR, you'll never
get to 100% accuracy, so you'll always be correcting errors.
I would try these other avenues before I scanned a statement:
1. Can you download your statement in some format (csv, excel,
quicken/money)?
2. Can your broker send you a file that you can import?