How do I "Show Documentation" in Eclipse?

I've never used IntelliJ, so not sure it's an exact equivalent, but when I press F2 in Eclipse, I have a popup that displays some help.

For example, here, I pressed F2 as my pointer was on Log :

_{(source: pascal-martin.fr)}

To see the attached Javadoc of a class, you can open the Javadoc view in another panel by pressing Alt + Shift + Q, J (as described in this answer). Alternatively, select "Window -> Show View -> Other -> Java -> Javadoc". The view will be updated with the selection in the code editor and will show the Javadoc for the method, class or even field at the cursor position.

I don't know if there is anything similar for other languages though.