What if the IT guy dies?

I work or a company with approx 50 employees and we currently have one employee heading up the IT dept. At this time nothing he handles is documented; network topology, admin passwords, server specs, licensing info… in short everything IT related resides in his head only. So what happens if he dies one day, are we screwed? Generally speaking I would expect this type of info would be documented as a security measure. Therefore if it could not be handled in-house we could at least hire an outside source and keep things running smoothly.

Any thoughts?

BTW, for job security reasons presumably, he has avoided documenting or sharing this info. How can I tactfully request this information?