American Idol , whose ratings often drop when it airs on Thursdays (it did so this week because of President Obama's address to Congress on Tuesday), did indeed see its numbers take a tumble Thursday night -- but so did just about every other television show. Idol averaged 20.7 million viewers, low by Idol standards, but good enough to beat every other show that aired Thursday night. By contrast, CBS's Survivor , which aired opposite Idol, averaged 12.3 million. Last week it drew 13.7 million.