Powershell IDE - Syntax checking, refactoring, ...?

Hi,

I'm now using powershell for a while. And I like the extending of the old batch.
But I'missing a good IDE for using the power of the powershell.
For C# I have Visual Studio - but nothing for powershell.
I want Syntax-Highlighting, Syntax-Cheking (is something missing?), auto completion (also extern Libraries)
Support for refactoring and debugging, also It should help me quickly get to the documentation of a command/-let
(ISE does not have them or are they somewhere hidden?)

Nothing aut there having all this features?