It seems to depend on your level (above or below L65 which is first Principal rung). 12 months of health insurance is nice, but the pay seems to be between 3-9 months worth of pay depending on various factors.

It's something like - 3 months base salary - plus either 2 weeks or 1 month of pay per year of service (the former if you are at principal level or above) - 12 months health insurance