The Federal Reserve discussed lending Lehman Brothers up to $200 billion in 2008 to rescue the struggling investment bank, according to a document released by the Financial Crisis Inquiry Commission on Thursday.

It is not clear from the document or others released by the commission how seriously Fed officials considered the idea. The Fed and Treasury Department ultimately decided against helping Lehman with special assistance beyond emergency programs it established for other firms at the time and it ended up filing for bankruptcy.

The document, a compilation of emails among top Fed officials including chairman Ben Bernanke, was one of hundreds released with the commission's report on the causes of the financial crisis. The emails were provided by the Fed to the commission as part of its investigation.

The email about a possible loan of historic size was written by Patrick Parkinson, then the deputy director of the Fed's division of research and statistics, in July 2008. The subject line of the email was "Our Options in the event of a Run on LB."

In a "run" on a financial firm, worried customers demand the return of their cash or investment securities so quickly and in such large amounts that it puts the firm's survival at risk.

"Even if we are willing to extend as much as $200 billion of financing to LB, absent an acquirer our action would not ensure LB's survival," Parkinson wrote Bernanke and other Fed officials. "That's not to imply that it would not be worth the gamble, but it would be a gamble."

You can read the email discussing Lehman's survival for yourself here.

At the time, the Fed, the Treasury Department and other regulators were racing to prevent a collapse of the U.S. and global financial systems. Reports, records and testimony since then show they considered every option, many of them unprecedented.

Officials evaluated a number of steps to help Lehman, including seeking a buyer for it.

While they did not rescue Lehman, the global shockwave of its failure convinced them to bail out insurance giant AIG a week later, in a package eventually valued at $182 billion, the largest of the financial firm rescues. That October, Congress approved the Bush Administration's $700 billion TARP program to provide necessary taxpayer funding to banks.

In testimony to the financial crisis commission in September last year, Bernanke told members, "I wish we had saved Lehman but it was beyond our ingenuity and capacity to do it."

Among other things, Bernanke said the central bank did not have the legal authority to rescue Lehman with loans because the company did not have enough capital to assure repayment.

A spokesperson for the Fed did not immediately respond to a request for comment.