You don't specify if you're talking about the Legacy PlugIn or the full OpenStudio release. If the latter, take a look at this thread. Only the Legacy PlugIn has the ability to completely read and write IDF, and it is only updated when major version changes in EnergyPlus or SketchUp occur. The OpenStudio project has long since moved on from importing IDF, and the SDK is focused on helping developers efficiently author EnergyPlus (and Radiance) input files for single or portfolio-scale analysis. Certainly for portfolio-scale analysis there's no need for SketchUp.