Steven Rothmeier, the no-nonsense executive who remade Northwest Airlines in the 1980s only to lose control of the company to a debt-fueled buyout, died Thursday in a Florida nursing home.

Rothmeier, 67, had suffered from Lewy body disease, a type of progressive dementia, and Parkinson’s disease, which he’d struggled with for several years, said his brother Michael.

Jay Rothmeier, a brother and business partner, confirmed the death Friday.

Rothmeier joined Northwest in 1973 after a stint at General Mills. He was a decorated infantry officer in Vietnam and earned an MBA from the University of Chicago.

Rothmeier became part of a longtime Northwest management group that focused on keeping a strong balance sheet, safe operations and staying profitable during a time when many competitors, freed by deregulation to choose their own routes and fares, got into financial trouble.

In 1985, at age 38, Rothmeier was named Northwest’s CEO. The next year, he engineered the merger of Northwest with Twin Cities-based Republic Airlines. At the time, the deal was the largest-ever airline combination. Through it, Rothmeier added new routes, new hub cities in Detroit and Memphis, and gave NWA one of the broadest reaches among airlines, with service from Europe, across the United States to the Pacific Rim.

“Steve was one of the brightest guys I ever worked with or for and he was a strong leader,’’ recalled John Horn, a retired Northwest senior executive. “He took what [former CEOs] Donald Nyrop and Joe Lapensky gave him and grew it successfully. And then we got caught in the takeover game.’’

While the Republic deal was a strategic success, its execution proved chaotic for passengers and employees. Rothmeier was criticized for a style that some called too strict, too focused on lean operations, and inattentive to customer service.

By 1988, Rothmeier was appearing in ads saying the carrier could do better and announcing new customer perks. But his days as CEO were numbered.

Within a year, Gary Wilson, a Northwest board member, stepped down and joined with California financier Al Checchi to lead a debt-heavy buyout of what had been a conservatively financed NWA. Rothmeier stepped aside by late 1989.

The debt load imposed on NWA nearly bankrupted it in the early ’90s. But the routes and hubs that Rothmeier added remained key strengths until NWA merged with Atlanta-based Delta Air Lines in 2008.

Rothmeier could be brusque, but usually not intentionally so, associates said.

Brent Baskfield, a Northwest executive who served under Rothmeier, recalled that he often concluded employee meetings with a wave and the admonition, “Work hard.” Once, a ticket agent in Los Angeles broke down in response, saying she was working as hard as she could. Rothmeier wrote her a note of apology, saying he appreciated her hard work, Baskfield said.

“He never concluded another meeting saying, ‘Work hard,’ ” Baskfield said.

“Steve Rothmeier was an academic success in graduate school, a war hero and a great industry leader,” he added.

Rothmeier also had a dry sense of humor, said Tim Thornton, a onetime Northwest general counsel who became Rothmeier’s attorney after they both left the airline. In 1988, Northwest settled labor contracts with its pilots before the same task could be accomplished by rival Steve Wolf at United Airlines — a CEO often viewed as more charismatic and better with people than Rothmeier.

“Steve Wolf is going to throw up in his wastebasket when he reads about this contract,” Rothmeier quipped, according to Thornton.

The oldest of three sons, Rothmeier came home from the University of Notre Dame to run and sell the family propane business in Faribault after his father was killed in a car crash. Rothmeier later returned to graduate from Notre Dame.

After leaving NWA, Rothmeier started a St. Paul investment firm, Great Northern Capital.

A bachelor and conservative Catholic, Rothmeier was a member of St. Agnes Church, a predominantly working class parish in St. Paul’s Frogtown area known for its Latin high mass. He was a donor and former volunteer football coach at St. Agnes High School.

For years Rothmeier cared for his mother, who lived with him at his Bavarian-style compound in Eagan, complete with a chapel. Last year, Rothmeier put the property up for sale.

His family plans to announce funeral arrangements at St. Agnes next week.