From what I gathered from the comments, let me make an assumptions to the application:
-The list of documents will not be modified frequently. Besides initial configuration, an administrator will not be using/modifying the list frequently.
Also, this answer is based off of the layout of the page/actions (as that is what I believe you are asking), not the design of buttons, or location of buttons.
To answer your initial question on whether or not it's a cascading list, it is not (but has potential to depending on how you plan on navigating).
Let's first state that we want the user to be able to accomplish their tasks with the least amount of clicks, and the most amount of comprehension and intuitive actions.
Now, a use case. Suppose the user navigates to this application and hits the Documents panel. Chances are, they are there to modify the All Documents tab (that can change depending on how you feel the users are using the application), so they will not have to click again on one of those tabs, it opens one automatically. So the user clicks Documents, and the All Documents tab is automatically selected, and the list of documents is already shown. At this point, modifying a document is only one more click (selecting the document to edit). Listing our action steps, we have:
1. Select Documents
2. Select Document to edit
These kinds of clicking actions make sense, and are intuitive. I want to modify a Document, so I click the Documents navigation (on the left), and then select the desired document.
I agree that a modal dialog for accomplishing this would be a bit much and cumbersome. With this UI, the user can easily navigate to the desired document to modify, but then quickly return to Home, or Products.
Additionally, this design has a good separation of functionality. There is a clear line between navigation, actions, and configuration, with having the "3-Panel" layout. And I know you said you weren't looking mobile, but it is good to note that a design like this allows for easy mobile design in the future (by ultimately making it a drill down, or a compressed drill down).
To answer your other question, is there a better option?
I might make the argument that there is always a better option, but those options typically only present themselves with time. A design that was great 10 years ago may not be great today. Based off what I'm seeing/hearing, this design would accomplish your tasks. So the question arises, have there been any negative comments to this design that you have received?