"Downloading Maven sources and documentation"

I work on several maven projects and I see IDEA doing this all the time. Many times, errors won't resolve until this is done. Maven stores a local repository (~/.m2/repository) that holds most of the binaries, so the errors should resolve quickly.

1. What is IDEA doing and where is it saving the sources and documentation it's finding? Is it not caching them?
2. Is there a way to see more information on what IDEA is doing? Where it's looking? What file(s) it's downloading?