No difference! They are exactly the same.

I disagree with Alex. The conjugated "to get" in the former expresses the obtaining or receiving of an idea, whereas the latter purely expresses "not having". Further it would be "an idea" or "any ideas" but "any idea" is incorrect. Further if you wish to communicate "better" English then there are superior ways to say "have got", such as "have received". I say "better" because, as above, using that form of to get is ambiguous... have you not received an idea or do you not have one.

I can assure you that there is no difference at all between these two sentences. The meaning is exactly the same.