Intellij Idea is an advanced and mature IDE capable of supporting an ever impressive list of languages and is available for linux, mac and windows.
IntelliJ IDEA had a Haxe plugin but it is currently broken and unmaintained. According to the comments, IntelliJ is looking for someone to fix the plugin, which might imply monetary compensation (you could at least ask for a free IntelliJ license). You should be able to use the IntelliJ TextMate plugin to get syntax highlighting.
There are many things about the IDE that are of benefit to any language you use idea for, such as amazing Version Control Integration, advanced code refactoring, sdk and library management, code completion/generation, code analysis, flash debugging, code formatting, color themes and the list goes on.
The Haxe Plugin currently has a dependency of the "Ultimate" version of Idea which is a paid for commercial app. IntelliJ IDEA Ultimate are provided with the 30 days trial period. There is also an opensource "Community" edition that has great Android/Java support.
Jetbrains have a very active issue tracker where Haxe issues/features etc are being taken monitored by the hard working devs.