Idaho Code § 35-105
When one (1) of such adjoining proprietors has allowed his land to lie uninclosed, and afterward incloses it, he owes and is indebted to such adjoining owner one-half (1/2) the value of any division fence owned by the other, used by him in forming such inclosure; and each must thereafter keep one-half (1/2) of such fence in repair.
[(35-105) 1885, p. 118, sec. 1; R.S., sec. 1304; reen. R.C. & C.L., sec. 1268; C.S., sec. 1960; I.C.A., sec. 34-105.]