Portneuf Medical Center | EastIdahoNews.com file photo POCATELLO — Many southeast Idahoans are on the brink of losing coverage as Portneuf Medical Center and one of the area’s top insurance providers struggle to reach an agreement on costs. Regence BlueShield of Idaho, one of the top insurance providers in the area, recently announced that they are in negotiations with Portneuf Medical Center, which is owned by both Ardent Health Services and th…