Northwest unexpectedly filed its reorganization plan today with a federal New York bankruptcy court.

It was somewhat unexpected in that the plan was not due until Jan. 16. According to the airline, the plan was filed ahead of the deadline in an effort to avoid “interference” from “outside parties.”

Hmmm. Okay.

Another interesting aspect of this filing was that while the basic plan was filed, the more detailed disclosure statement was not filed.

That is where the nuts and bolts details of the airline’s plan are more clearly spelled out. Especially in reference to how it plans to pay its creditors.

However, because the airline has not yet filed its disclosure statement, a merger or other deal with Northwest is still a possibility.

Northwest’s plan gives it the option to raise money by selling equity in the restructured company and possibly raise capital from private equity firms. The company also plans to convert its existing bankruptcy financing into new forms of debt.

The new debt would include a $175 million revolving credit facility and a $1.05 billion loan, including a $75 million letter of credit, each with a maturity date of August 2013, the airline said.

And, as we all expected, existing shares of the airline will become nothing more than wallpaper.