Do you have an employment agreement or contract with your employer? Most will ask you to sign something that says all the ideas you have while working for them

Do you have an employment agreement or contract with your employer? Most will ask you to sign something that says all the ideas you have while working for them (related to your job) belong to them, regardless of when you come up with them. While the enforcability of such clauses may be questionable they can probably tie you up in court long enough to make your idea worthless, or at least to give themselves long enough to run with it.