Idaho is one of 18 states that allow felons to vote after they have completed their sentence, including probation and parole. That includes felons from other states who have completed their sentences and relocated to Idaho.
According to this recently updated chart at procon.org
there are a dozen states that deny convicted criminals their right to vote for life, even after completing their sentence. Arizona, and Nevada are on this list, as is Florida
There are some 20 states (and the District of Columbia) that are less restrictive than Idaho, letting probationers vote, or as in Maine and Vermont, allowing prisoners to vote from prison.