A Wichita real estate firm wants to transform the massive Overland Park International Trade Center into an appealing address for companies seeking contemporary office space.

Occidental Management has bought the 650,000-square-foot building at 115th Street and Metcalf Avenue near the Sprint campus for about $20 million. The huge center opened in 1986 and has been the venue for a variety of events and served as a wholesale showroom for retailers.

Now Occidental would like to keep its primary tenant, UnitedHealth Group, which occupies about half the space, and convert the rest of the two-level building into premium office space.

"The geography is tremendous," said Gary Oborny, chairman and chief executive of Occidental. "The property needs to be rebranded and repositioned as an office campus. That's the basis of what we'll do."

This is Occidental's first venture into the Kansas City real estate market.

The company was founded in 1997 and controls about 1 million square feet of retail, office and industrial property in the Wichita area. Oborny said it has an additional 1 million to 1.5 million square feet of space under development in Kansas and Oklahoma.

Chad Stafford, the president of the firm, is an Overland Park native. He said the plan for the trade center calls for it not to be a "typical glass and brass office."

"We want a warm, contemporary look to fit today's employer's needs - open floor, collaborative workspace," he said.

Because of the large size of the vacant floor, about 325,000 square feet, Occidental officials believe the building can accommodate firms seeking anywhere from 25,000 square feet to the full floor. Plans also call for skylights to be introduced to bring additional natural light and tenants to have their own entrances rather than a shared lobby.

A 51,000-square-foot convention center annex added in 2005 will continue to accommodate conventions.

The building was purchased in 2006 by Rubicon Investments of Atlanta for $46.5 million. The property went through foreclosure and was sold to Occidental. Oborny said his company had wanted to buy the trade center for several years and closed on the property in April.

Rod Jones of Colliers International represented the building's ownership.

Occidental plans to invest $20 million to $30 million to address deferred maintenance issues and renovate the building. The bulk of the work is not expected to start until a significant new tenant is signed. Work has begun on some interior demolition.