There is only one way to be sure. You will need the following:
1. Sentry Fire Safe, matching the type you intend to use.
2. Some important papers. Using unprinted blank sheets of paper or unimportant papers might skew the results.
3. A firearm matching the type you intend to keep in the safe.
4. Said firearm loaded with the ammo you intend to keep in the firearm in the safe.
5. One gallon of gasoline.
6. One Zippo lighter.
7. Someone to hold your beer and watch while you...
I don't know man. I don't think it would. If M2 Carbine spots this he might have something firsthand. He went through a fire. I suppose the only way to truly be 100% sure is to keep it in something separate from your papers.
I would also add that scanning your papers and placing the files on an encrypted thumb drive that you store elsewhere is a good thing to do.