If you're a Google Docs power user, you should start using the Version history feature to help save you from when something goes disastrously wrong with a document.

Select File > Download > PDF Document (.pdf). Save the PDF to your computer. You can name it whatever makes sense to you, and save it to whatever folder is most appropriate.

Open Google Docs. If you're not logged in to your Google account, you'll need to do that now. Select File > Download > PDF Document (.pdf). Save the PDF to your computer.