How to change document units?

I have some documents in Points that I want to set to Millimeters using a JSX script, then save them.

I have tried the following code:

var document = app.activeDocument;

document.rulerUnits = RulerUnits.Millimeters;

document.units = RulerUnits.Millimeters;

After executing, the document (File > Document Setup > Units) and the ruler are still in Points.

Is it possible to change the unit by script?