Yes, I second the comments from Bob_NC, the KH's are essentially self-insured, through "Mother". I spent many years handling Accounting at the KH level, and there was NEVER a payment made to a third-party insurance company (like Allstate, Farmers, etc.) As Bob said, there is a set amount per publisher as a "recommended" donation, yearly. There is no special fund, it all goes the great and wondrous WWW (world wide work).
However, the times they use "insurance" is Very VERY rare. I can think of 1 KH that burned in the Portland, OR area about 12 years ago or so. Then, everything goes thru the RBC. Other than that type of thing, any "claims" are strongly discouraged. Publishers are encouraged to use their own insurance if they hurt themselves on KH property, etc. Yep, another income stream. Kinda like the old "Parking Ticket" scam at the Tacoma Dome from years gone by.