Did she come to America with any other family members? Did she spend any time in the USA before she lived in Idaho?
YOu could contact the Lemhi County Clerk, 208-756-2815 and ask if they have a way to look up her marriage under her maiden name.
I checked the Western States Marriage data base and didn't find her there but that's assuming she married in Idaho.
Hopefully the "Norway expert" will see this post and be able to help you. Successful Searching!