What is the size of the Large HTML field

I am importing csv from our old bug tracking system - in that system some of the descriptions are quite large. It appears that it hits the size boundary and then just skips the rest of the information.

Description is Large HTML - but there is no indication about the size boundary of this.

So do you have a document that tells the size of the different attribute types that are used? It will make it easier and give a better indication of accuracy when doing the import if I test the field sizes when generating my csv file.