DETROIT (AP) — General Motors plans to sell 20- and 30-year notes to make a payment on its huge U.S. pension obligation for hourly workers.

The Detroit company filed a prospectus for the offering with U.S. Securities regulators on Thursday that did not specify an amount. But Moody's Investor Services said it would be $2 billion.

At the end of last year, GM's U.S. hourly pension plan was underfunded by $10.4 billion. About $61 billion of the obligations were funded for the plan's roughly 360,000 pensioners.

GM says in a statement that any proceeds that are left over from the discretionary payment will go for general corporate purposes.