eclipse is the best c ide out there at the moment for non-ms platforms.
intellij idea used to have a third-party c/c++ plugin, which was ok, but it stopped being maintained a while back. this was frustrating because otherwise you can develop in intellij in most popular languages. so c/c++ support had been a strange omission for some time - see this support issue, for example - http://youtrack.jetbrains.com/issue/IDEA-86304
(i haven't seen anything saying that this will be an intellij idea plugin - but afaik that's how all their other products work).
intellij idea used to have a third-party c/c++ plugin, which was ok, but it stopped being maintained a while back. this was frustrating because otherwise you can develop in intellij in most popular languages. so c/c++ support had been a strange omission for some time - see this support issue, for example - http://youtrack.jetbrains.com/issue/IDEA-86304
(i haven't seen anything saying that this will be an intellij idea plugin - but afaik that's how all their other products work).