Laurance S. Rockefeller was awarded the Congressional Gold Medal in honor of his philanthropic work.

NEW YORK (CNN/Money) - Laurance S. Rockefeller, a billionaire philanthropist who was well-regarded as a trailblazer of modern venture capitalism, died in his sleep Sunday at the age of 94, the New York Times reported Monday.

The Times, in its obituary of Rockefeller in Monday's edition, said a family spokesman attributed the cause of death to pulmonary fibrosis.

Laurance Rockefeller, the middle brother of the five prominent grandsons of John D. Rockefeller, began his career on Wall Street almost 70 years ago.

In the decades since he first took his seat on the New York Stock Exchange, Rockefeller shrewdly invested in hundreds of start-ups in aviation, electronics and computers, including Intel (INTC: Research, Estimates) and Apple Computer (AAPL: Research, Estimates), the Times said.

However, the more reserved and private of the Rockefeller grandsons also wrestled with the question of how he wanted to use his millions.

As a philanthropist, Rockefeller helped develop national parks in Wyoming, the U.S. Virgin Islands and Vermont, and chaired the White House Conference on Natural Beauty, the Times said.

He also served on dozens of federal, state and local commissions, and advised every president since Eisenhower on issues involving recreation, wilderness preservation and the ecology, the paper said. In 1991, his philanthropic work earned him the Congressional Gold Medal.