In the case of Idaho, all forms of gambling except for those specifically authorized by the state are illegal and are considered a Misdemeanor.
Misdemeanors are usually punishable with up to six months in jail, a $1,000 fine, or both in the State of Idaho.
Idaho law is unusual in that it does not seem to differentiate from illegal operators and players.

As was mentioned in the restrictions page:
This is one incident in which law enforcement said that illegal gambling is not something that they would normally be looking for.
From the article:
"We've had very, very few gambling arrests," said Harrington, who has led BANDIT since 2003. "This is the first time I personally participated in the bust of a gambling operation. Most of the time, we send our community policing team to a gambling complaint and they usually issue a warning," he said.
This was dealing with an actual live gambling operation, as opposed to online. The operators and players were all pretty surprised not to just get a warning with no other action taken again.
As it turns out...
...law enforcement all but said they wouldn’t even have investigated in the first place, but once a complaint is called in, they basically have no other choice.
With all of that out of the way - it is extremely unlikely that you are going to get in any trouble for gambling online from your own home and we are certainly aware of no such incidents of that occurring. The only conceivable way that it would be investigated is if someone were to call in and report that you were doing it, and even then, it’s very difficult to believe that the police would ever care about a single player playing from his or her own home.
For this reason, almost all online casinos that operate within the United States also do so in the State of Idaho, and here are some of them below: