In my ~/.ideavimrc file, I set
noremap jj <Esc>
To remap "jj" to escape (to enter normal mode).
However, it doesn't seem to be working. File .ideavimrc is in the same location as my .vimrc file, and I restarted IntelliJ.
I don't believe multi-key mappings work. I can't find an open ticket, but that’s what Twitter comments suggest here and on Support 'jk' keyboard chord to exit Insert mode.
You can also check which mappings IntelliJ knows about by typing :noremap. Since jj shows up it probably doesn't work.