Louisville-based insurer Humana says it's not yet clear what a contract extension from the U.S. Defense Department will mean for the company.Earlier this year, Humana lost a bid to continue its contract to provide benefits for service members in the southern United States. The company filed a complaint and the Defense Department agreed to re-evaluate its decision.In the meantime, the contract has been extended through March 2011. Humana spokesperson Tom Noland says the extension is a positive development, but it's not yet clear what the extra time will be worth."On February 1st, 2010, we will assess quantitatively the impact, or the likely impact—the predicted impact—on the 2010 result of these decisions," says Noland.Last year, the contract represented about 11 percent of Humana's revenue.