St. Luke’s Health System grew rapidly over the past decade — acquiring and making deals with Idaho and Oregon medical practices and hospitals. As it grew, St. Luke’s executives described a master plan to curb the costs of health care — and to ensure that care actually makes people healthier. One milestone in that plan arrived last fall: a new insurance company called St. Luke’s Health Plan. “The thing that really is going to be different with our own health plan: you will have an integrated experience,” said St. Luke’s Health Plan President Matt Wolff. “I think that’s a major hurdle that causes a lot of friction, a lot of…