Give Visual Studio Code a look together with the first-party C++ Extension -- its a lightweight code environment that's partway between an IDE and simpler programmers' editors.

It doesn't have as good of intellisense as Visual Studio (but its as good as CLion's) -- The debugger is pretty slick, too. VS Code itself supports Windows, Linux, and Mac -- the C++ extension supports GCC on all of those platforms, but Windows is (surprisingly) the least mature (but then you have VS Community for free on Windows). Last I looked, CMake was a work in progress, but should be coming along quickly.

Visual Studio Code looks great, but the docs for the C/C++ extension say it doesn't have proper Intellisense support yet. It uses tag-based completion for now. Without Intellisense I suppose it can't do dynamic error checking either, so for now it can't match vim + youcompleteme or the Emacs equivalent. VSC does have a vim extension though, which already looks quite usable if that page is to be believed. Last time I checked Atom its vim mode wasn't up to the job, but that was a while ago.