Idaho law requires proof that a person was operating a vehicle and that the person was under the influence of alcohol or an intoxicating substance at the time. Operating a vehicle is defined as having been in the drivers position while the key was in the ignition. In order to prove a DUI case against you, the prosecution will have to present evidence that persuades your jury that you actually were operating a vehicle at a time relevant to the charges, and that you were under the influence at that same time. In cases like yours the police will typically testify to your car being on the road at time shortly before they came to your house. That alone though is insufficient, they will also have to show that you, personally, were actually operating the vehicle. In a case like yours it all comes down to the specific facts which can be admitted into evidence before the court. I strongly advise that you contact an attorney and discuss the particulars of your case as soon as possible. Also, you should be mindful that you have only 7 days from the time you were charged to request a hearing or your license to drive will be suspended (depending on the circumstances) from 90 days up to a year. If you do not meet that deadline you will be stuck with the suspension even if you beat the DUI charge itself.
If that truly is the case it would be well worth the money you would spend on hiring an attorney. The fines you would have to pay would likely be more then the retainer. At least schedule a time to tell an attorney the facts. Also remember you have really strict time limits on things with a DUI. Two different hearings for driving/criminal. Best of luck!