I use macType which renders fonts beautifully elsewhere except Intellij.
I tried to configure Intellij through these Java options
-Dawt.useSystemAAFo
Java applications don't work well with MacType. Take a look at the discussion here: https://code.google.com/p/mactype/issues/detail?id=53
You could try gdipp instead. https://code.google.com/p/gdipp/. You may have to set the embolden parameter in its settings file to 6 or 7 atleast for all the glyphs to display correctly.
Intellij does not allow you to choose Ubuntu Bold because it is not a monospace font, but if you check Show Only Monospaced fonts, it should work.