Sony Group Corp. said Tuesday that Nobuyuki Idei, its former chairman and CEO, has died of liver failure. He was 84. In addition to enhancing the Japanese group's presence in the digital and communications fields, he also focused on the entertainment business, such as movies, music and game consoles, laying the foundation for Sony's current operations. He joined Sony in 1960, becoming president in 1995 and CEO in 1998. He served as both chairman and chief executive from 2000 to 2005.