Idiomatic language does not mean idioms, idioms are a type of idiomatic language, phrasal verbs are a type of idiomatic language, slang, colloquialisms, local language that you'll hear around here, that's another.
地道的语言不等于成语,成语是一种地道的语言,短语动词是一种地道的语言,俚语,口语,你会在这里听到的地方语言,那是另一回事。