Robert B. Wegman, 87, who introduced the idea of one-stop shopping at his family-owned chain of supermarkets, which are the envy of the industry for their unparalleled levels of customer and employee loyalty, died April 20 at Strong Memorial Hospital in Rochester, N.Y. The cause of death could not be learned. In more than a half-century at the helm of Wegmans Food Markets Inc., Mr. Wegman built an innovative company that combined business success and humanitarian ideals. He pioneered the concept of one-stop shopping and the superstore, with bakeries, imported foods, cafes and photo labs all under one roof. He...