BUTTE, Mont. and SIOUX FALLS, S.D., July 23, 2019 /PRNewswire/ -- NorthWestern Corporation d/b/a NorthWestern Energy (NYSE: NWE) reported financial results for the three months ended June 30, 2019. Net income for the period increased 8.9 percent to $47.7 million, or $0.94 per diluted...