Fast National ratings for Thursday, April 18, 2013.
 
Although it was down from last week, "American Idol" still carried FOX to a slim Thursday win among young viewers, while comedy repeats played a big role in CBS' slim overall win.
 
Meanwhile, despite an improved lead-in courtesy of "Parks and Recreation" rather than "Go On," NBC's "Hannibal" took a dip in its third episode. 
 
Of course, live news coverage of the overnight shocking events in Boston began breaking in earnest late in primetime for much of the country and it remains to be seen whether there was a massive cable news spike in the 10 p.m. hour.
 
Among adults 18-49, FOX averaged a 2.5 rating for Thursday primetime, edging out the 2.3 rating for CBS in the key demographic. [CBS actually won the two primetime hours in which the networks went head-to-head.] NBC was third with a 1.4 key demo rating, followed by ABC's 1.2 key demo rating. The CW averaged a 0.7 key demo rating for the night.
 
Overall, though, CBS averaged an estimated 9.25 million viewers and a 5.9 rating/9 share, nipping the 5.8/9 and 9.14 million viewers for FOX. There was a big drop to ABC's 2.7/4 and 4.03 million viewers, which topped the 3.18 million viewers and 2.0/3 for NBC. The CW averaged a 1.2/2 and 1.87 million viewers for Thursday night.
 
8 p.m. - "American Idol" was off from last Thursday's show, but still drew 11.9 million viewers and a 2.9 rating among adults 18-49 to win the 8 p.m. hour for FOX. CBS was a solid second with repeats of "The Big Bang Theory" (11.19 million and a 3.0 key demo rating) and "Two and a Half Men" (8.73 million and a 2.3 key demo). ABC's "Wife Swap" was third with 4.73 million viewers and a 1.5 key demo rating. NBC finished fourth with a new "Community" (up with 3.19 million and a 1.3 key demo) and an "Office" repeat (2.31 million and a 1.0 key demo). The CW's "The Vampire Diaries" averaged 2.14 million viewers and a 0.9 key demo rating.
 
9 p.m. - Repeats of "The Big Bang Theory" and "2 Broke Girls" won the 9 p.m. hour with 9.22 million viewers and a 2.7 rating among adults 18-49. FOX's "Glee" averaged 6.39 million viewers and a 2.2 key demo rating, down from last week and likely to drop more due to multiple minutes of "Idol" overrun. ABC's "Grey's Anatomy" repeat averaged 3.98 million viewers for third and a 1.1 key demo rating for fourth. NBC's two episodes of "Parks and Recreation" averaged 3.295 million viewers and a 1.7 key demo rating, collectively up from last week's telecast. The CW's "Beauty and the Beast" averaged 1.6 million viewers and a 0.6 key demo rating.
 
10 p.m. - A repeat of "Person of Interest" improved over last week's "Elementary" repeat numbers for CBS and won the 10 p.m. hour with 8.56 million viewers and a 1.7 rating among adults 18-49. NBC's "Hannibal" dropped to 3.5 million viewers and a 1.4 key demo rating, though numbers last week improved between Fast Nationals and Finals. ABC's "Scandal" repeat averaged 3.37 million viewers and a 0.9 key demo rating.
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.