If you want to stick a little more with IntelliJ IDEA 15, consider upgrading to 15.0.5, which update includes several important bugfixes.
You can update from the IDE, by clicking Check for Updates (make sure you've set the update channel to Milestones Releases, though, or you'll get IntelliJ IDEA 2016.1 instead):
Or, you can do that the good old way: download an installer from here, and open it on your machine.
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The JetBrains Team
The Drive to Develop
