David Letterman to retire from 'Late Show' in 2015

During a taping of Thursday's show, Letterman said he has informed his CBS bosses that he will step down in 2015, when his current contract expires. Letterman turns 67 next week. He has the longest tenure of any late-night talk show host in U.S. television history, nearing 32 years since he created "Late Night" at NBC in 1982.