Should I negotiate my severance?

I was offered 12 weeks of severance after 12 years as a customer-service rep, and I have a few days to sign. I am in Hartford, in case local advice matters. It includes health coverage for a couple of months. Did anyone negotiate and succeed?

Ask for the offer in writing and do not sign on the spot. A day or two to think is normal.

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.