This only works depending on how diligently you formatted those TODOs. Before you know it your regex explodes. I use IntelliJ as well, so I don't have to think about these problems.
I mean, how often do you place the four characters "TODO" in your code when you don't mean to mark a TODO? The only common English word I know of that contains that substring is "mastodon", and it'd have to be all-caps.