NEW YORK (AP) — The long goodbye is under way for "American Idol." Fox says it will take the show off the air after next season. And during the 15th and final season, former judges and contestants will take part in the farewell. Idol used to be a ratings juggernaut — but its audience has dropped in recent years. And while changes in the judges' chairs and tweaking the formula have helped keep the show afloat, it seems to have fallen victim to the same malady that eventually dooms most TV shows: old age and falling viewership.