Night two of “American Idol” lifted Fox to No. 1 in the ratings by a wide margin on Wednesday. According to Nielsen’s estimates, the reality show drew an average of 26.3 million viewers, down from the 29.9 million who watched the season premiere on Tuesday. It was followed on Fox by a repeat of the 450th episode of “The Simpsons” (8.1 million). CBS ranked second, drawing low ratings for its comedies “The New Adventures of Old Christine” (6.3 million) and “Gary Unmarried” (5.8 million), but better results for its crime shows “Criminal Minds” (14 million) and “CSI: NY” (14.1 million). NBC was third with “Mercy” (6 million), “Law & Order: SVU” (7.7 million) and “The Jay Leno Show” (5.4 million). ABC’s lineup of comedies finished the night in fourth place.