Aon Corp. said it plans to eliminate more than 1,500 jobs as part of its restructuring plan with the merger of Hewitt Associates.

In a filing with the Securities and Exchange Commission today, the insurance brokerage firm said with the completion of the deal to acquire Hewitt, Lincolnshire, Ill., a human resource and outsourcing solutions firm, it plans to establish a reorganization plan that will take until 2013 to complete.

The move is expected to “streamline operations across the combined organization,” Aon, Chicago, said in its filing.

The plan will cost $325 million and primarily involve layoffs and “real estate rationalization costs,” Aon said. About $180 million of the cost will go to layoffs and the remaining $145 million to real estate.

The layoffs are estimated to number between 1,500 to 1,800 positions globally, “predominately non-client facing,” the company stated.

The streamlining is to result in annual savings of around $355 million in 2013, with additional savings in the areas of information technology, procurement and public company costs.