DETROIT — General Motors took a huge step forward today in ending its ownership by the government, filing paperwork that gave the price range and other details of a planned initial public offering.

The company also forecast that it earned as much as $2.1 billion from July through September, a strong financial performance as the company prepares for an initial stock offering on Nov. 18.

The third-quarter earnings, which GM will report next week, bolster the automaker's contention that it is leaner and more profitable since restructuring under a government-funded bankruptcy last year.

GM earned $2.2 billion in the first half after it cut brands, lowered debt and offered popular new models of cars and crossovers.

But those six months of earnings could almost be matched in the third quarter alone, if GM's most optimistic prediction pans out.