This method can be used to create a launcher for any application, not just IntelliJ IDEA. For any launcher in Unity what you need to create is a .desktop file.

First create a file named idea.desktop in your home folder. Then open it with a text editor and add the following to it.

[Desktop Entry]
Name=IntelliJ IDEA
Comment=IntelliJ IDEA IDE
Exec=/home/nufail/apps/idea-IC-107.587/bin/idea.sh
Icon=/home/nufail/apps/idea-IC-107.587/bin/idea_CE128.png
Terminal=false
StartupNotify=true
Type=Application
Categories=Development;IDE;

nautilus-actions.org gives a good explanation about .desktop files and what all these entries mean and other entries available for .desktop files.

Now you can keep this file in the Desktop to use it as a desktop launcher or you can add it to ~/.local/share/applications to access it through the Dash for only the current user. If you need to access it through the dash for all users, then add it to /usr/share/applications.