Former Secretary of State George P. Shultz, a titan of American academia, business and diplomacy who spent most of the 1980s trying to improve Cold War relations with the Soviet Union and forging a course for peace in the Middle East, has died. He was 100.

Shultz died Saturday at his home on the campus of Stanford University, where he was a distinguished fellow at the Hoover Institution, a think tank, and professor emeritus at Stanford’s Graduate School of Business.

The Hoover Institution announced Shultz’s death on Sunday. A cause of death was not provided.

A lifelong Republican, Shultz held three major Cabinet positions in GOP administrations during a lengthy career of public service.

He was labor secretary, treasury secretary and director of the Office of Management and Budget under President Richard M. Nixon before spending more than six years as President Ronald Reagan’s secretary of state.