Aon will cut 1,500 to 1,800 jobs over the next three years, the insurance conglomerate said Thursday, two weeks after closing its acquisition of Hewitt Associates.

A broad restructuring of the company will be completed by the end of 2013 and Aon said it expects to save $355 million per year, including $280 million per year by eliminating jobs.

Aon closed its $4.9 billion acquisition of Hewitt Associates, a human resources specialist, this month. The company has about 36,000 employees, including 29,000 in its Aon Hewitt human resources business. The job cuts announced Thursday will trim 4 percent to 5 percent of that work force.

The company said the plan will cost $325 million to implement, including $180 million in employee severance costs and $145 million in real estate expenses. It disclosed its plans in a filing with the Securities and Exchange Commission.

Shares of Aon Corp., world's largest insurance broker, closed at $39.46 Wednesday.