An idol is something given more devotion than it can bear. In a dream it is read as admiration that has turned into dependence, or as a question of what you have placed at the centre of your life.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.