I was a Delphi programmer for a few years, professionally, when it first came out in the 90s. I worked with their developer products (and for Borland directly on Delphi/Kylix/C++Builder, eventually) until the mid-2000s. I've never seen the match of Borland's docs, before or since, particularly as integrated with the IDE's coding features.
There are a number of programming languages and APIs with excellent documentation, but theirs were above and beyond.