unfortunately for terminal lovers, the best .gitconfig snippet is still this:

  [diff]
    tool = intellij
  [difftool "intellij"]
    cmd = idea diff \"$LOCAL\" \"$REMOTE\"
  [merge]
    tool = intellij
  [mergetool "intellij"]
    cmd = idea merge \"$LOCAL\" \"$REMOTE\" \"$BASE\" \"$MERGED\"
    trustExitCode = true