I do residential design work and use SketchUP for part of that work. I am starting to want to create a library of construction details that I can reuse in new projects - and occasionally edit them to fit the new context. The way I have been drawing details is to draw them in SketchUP but to dimension and label them in Layout because Layout is a much better place to do the text and dimension part. When I have created a detail for a given project that I think would be useful for other projects I would like an easy way to select that detail in Layout and copy it somewhere for use later. I think the way I would have to do that now would be to start a Layout sheet in a library directory to copy a selected detail to. I would then need to also copy the linked SketchUp detail to that library directory and re-link the Layout detail to that new location. It would be nice to be able to select and copy the desired detail into a new layout sheet in the desired library directory and have the SketchUP part automatically copy over to the same directory and re-link to the layout. The problem is complicated a bit by the fact that the SketchUP drawing within which the detail I want to copy has many other details there that I may not also want to copy. I would be happy to help brainstorm how to solve this problem with whomever is interested.
You want a scrap book.
You can use the scrapbook for simple details or even complex components which is what it’s designed for. Personally, rather than use the scrapbook (which I use extensively for line styles, various drawing symbols, text types etc) I’ve created a directory of individual Layout pages with specific components or assembly’s on each, and as long as they are unlinked from the original SketchUp file I can just copy and paste them into my new Layout pages without them linking back to SketchUp. As I write this I realise I could just list that directory as a scrapbook directory in preferences, but personally I prefer to copy and paste.
If you think you’ll occasionally want to edit the Layout details in SketchUp, just leave them linked and only unlink them once you’ve copied them into your new Layout file.
Hope that helps 
I have an ever growing library of scrap books I keep them organized by type. What I mean by that is I have symbol scrapbooks, schedule scrapbooks, detail scrapbooks and more. All are in a separate scrap book then within that scrap book are each specific part of the file. Scrap books can have multiple individual scrapbook items. When you edit this scrap book the individual files appear as a page in layout. While editing you can add a new page then import a SKP file annotate it name the page and save it into the scrap book. One tip is when editing that scrapbook “page” select all entities and group them, if you dont the labels, dimensions ect wont be visible.
In the image you see the scrap book detail being edited. its visible in the scrap book among the list of other details and in the page list. You see the SKP viewport and all annotations selected as a group. Once this is complete you save and close editing the when you want to add the scrapbook item to a drawing set its just a drag and drop like any other scrapbook item.