The reality show, which is set to enter its 12th season in January, saw declining ratings in its 11th season and there have been rumours of downsizing behind the scenes after the departure of judges Steven Tyler and Jennifer Lopez.
According to Ad Age figures, the advertising revenue has taken an expected hit, and is now a distant second behind American football coverage in the States.
Whereas last year NBC's Sunday Night Football and American Idol were effectively tied, with less than $10,000 separating them, now a 30-second spot during the NFL coverage at $545,142 (£340,425) commands roughly $205,000 (£128,013) more than a corresponding spot on Idol.
In the list of the top shows for advertising revenue provided by Ad Age, the top ten is rounded out by sitcoms (Modern Family, New Girl, The Big Bang Theory), and long-running animated shows The Simpsons and Family Guy.
This complete Ad Age list is as follows
1. Sunday Night Football - $545,142 (£340,425)
2. American Idol (Wednesday) - $340,825 (£212,829)
3. Modern Family - $330,908 (£206,636)
4. New Girl - $320,940 (£200,424)
5. American Idol (Thursday) - $296,062
6. The Simpsons - $286,131 (£184,496)
7. Family Guy - $276,690 (£172,799)
8. The Big Bang Theory - $275,573 (£172,098)
9. 2 Broke Girls - $269,235 (£168,140)
10. Two and a Half Men - $247,261