4 iconic American CEOs are on the way out. Meet the nuts-and-bolts leaders taking their place.

From left: Greg Abel, John Ternus, John Furner, and Josh D'Amaro. Getty Images Warren Buffett, Tim Cook, Bob Iger, and Doug McMillon are making way for a new crop of CEOs. The new bosses of Berkshire Hathaway, Apple, Disney, and Walmart are nuts-and-bolts leaders. But management gurus say that nailing the details isn't enough to succeed as a CEO. Four iconic American CEOs are making way for a new generation of business leaders. Warren Buffett, Bob Iger, and Doug McMillon have stepped down f...