I think greenpapers is off here.
This is the actual language from the Idaho Rules for the convention. (changed from 2014 to 2015 after Idaho went from a caucus to a primary)
http://s3.amazonaws.com/cdn.instabuildsites.com/uploads/files/a6d82db0cbd8339a8782b50c111bf30f.pdf
Article VI, Section 3(b) and (c) are relevant here.
(b) In order for a candidate to qualify for an apportionment of delegates, a candidate must receive at least twenty percent (20%), before rounding, of the total vote cast for all candidates in the Republican presidential primary. If a candidate fails to garner twenty percent (20%) of the total vote, the candidate does not qualify for an apportionment of
delegates, and delegates that would be pledged to such a candidate will be apportioned proportionally among candidates who clear the twenty percent (20%) threshold. Provided however, if no candidate clears the twenty percent (20%) threshold, the provisions of this subsection shall not be in effect, and delegates shall be apportioned proportionally.
(c) If any candidate receives more than fifty percent (50%) of the total vote cast for all candidates in the Republican presidential primary, all delegates available to Idaho under the Rules of the Republican National Committee shall be apportioned to that candidate.
Yes, I went back to the original rules, and you are right.