Bird ID [North Idaho]

North Idaho- I was hiking yesterday near a lake and saw a bird I'd never seen before. It sounded like a bald eagle, had an all white head, darker body, and what appeared to be blue under its wings. It looked like a hawk, smaller than an eagle. My birding buddy suggested an osprey based on what I just said but it did not appear to be one. I was not able to get any pictures, I apologize. Thank you for any help!