Idaho Code § 50-229
The hearing herein provided on said petition shall be held within the corporate limits of the city in which said lands sought to be detached are situated. The regular district court reporter shall reduce to writing the testimony and evidence introduced, the same as in trial of civil actions. The judge of such court, either before or after said hearing, may view the lands and premises sought to be detached, as well as other lands or property within the corporate limits of such city, which might in any way be affected by the granting of such petition, and lands on the outside of such city in the same vicinity or locality in which the lands sought to be detached are situated, and may consider such conditions as he finds in connection with the evidence introduced on the hearing, in making and arriving at his final decision and determination of the matter.
No tract or tracts of land shall be detached from any city which by such detachment, would materially mar the symmetry of such city.
Idaho Code § 50-229