American Idol used to get over 20 million viewers on a regular basis and was a constant at #1 in the ratings, but not anymore. Recent ratings have the show at #3 with about 12 million viewers.

It's hard to dominate the way Idol did for so long and, frankly, with that amount of viewers, most shows would do anything to have this "problem", but Idol has set the bar pretty high for itself over the years. 

Lots of things have changed about Idol, most obviously the judges. But there are other factors as well, like the amount of singing competition shows that are out there, including Simon Cowell's X Factor and of course The Voice.

Plus there may be a fatigue factor as well. I have been a huge Idol fan over the years, but I'm tiring of making a four or five hour committment a week to any one show. With all these reasons out there, it's no surprise that Idol is not nearly as dominant anymore.