If you rely on code-completion in your IDE, that should count as referring to language docs.
These days, for anything other than the trivial task, docs or code-completion are nearly a requirement. Even if you live and breath a modern language and associated libraries, almost no-one can remember the signature of *every* function, all the methods of every class etc. Hell, even the most commonly used methods might constitute several hundred functions. Too much to remember all that, plus the architecture of the application your building.