The accepted answer didn't work for me but I got everything working by doing this:
After reading various tutorials and messing with a bunch of fixes I've found a way that works perfectly.
First of all download JDK 8 from Oracle and execute the following lines in the terminal:
tar -xvf jdk-8u25-linux-x64.tar.gz
sudo mkdir -p /usr/lib/jvm/
sudo mv jdk1.8.0_25 /usr/lib/jvm/
Now download the JDK font fix (Courtesy of [Urshulyak Yaroslav]) by executing the following:
tar -xvf jdk-8u5-tuxjdk-b08.tar.gz
sudo mv jdk-8u5-tuxjdk-b08 /usr/lib/jvm
This will extract the downloaded zip and move it to /usr/lib/jvm/. Now run the following in the terminal:
sudo gedit .bashrc
Then add the following lines to the very bottom of the bashrc file.
Save it then gedit the idea.sh. (Your script location may be different)
At the very bottom of the script replace the line(s) in the While Do statement at the bottom with these two lines:
eval "/usr/lib/jvm/jdk-8u5-tuxjdk-b08/bin/java" $ALL_JVM_ARGS -Djb.restart.code=88 $MAIN_CLASS_NAME "$@"
test $? -ne 88 && break
Save it then open up IntelliJ, the fonts should work and you will be using Oracle JDK 8 for development. You will likely have to edit Project Settings and set up your JDK again but be sure to use the actual JDK and not the font fix one.
This fix also works with CLion, Android Studio and [PyCharm.
These instructions assume the JDK version was 1.8.0_25, file/path names will change for future versions.