The CW’s latest superhero drama, “DC’s Legends of Tomorrow,” opened to solid numbers on Thursday, a night won by Fox’s “American Idol” and also featuring third-week upticks for new series “Shades of Blue” on NBC and “Angel From Hell” on CBS — both of which may have picked up viewers who were watching the Republican debate last week. The Eye also had reason to be pleased by the performance on another rookie, “Life in Pieces,” which held at its recent level even with a repeat of “The Big Bang Theory” as its lead-in.

Looking at the preliminary Nielsen estimates for Thursday, “Legends of Tomorrow” opened with a 1.2 rating/4 share in adults 18-49 and 3.1 million viewers overall in the 8 o’clock hour, posting the same 1.2 rating in each half-hour; it also could edge up in the finals because it ran about three minutes into the 9 o’clock hour. The drama from Greg Berlanti, who also is behind the network’s “The Flash” and “Arrow” as well as CBS’ new “Supergirl,” beat ABC and NBC  in 18-49 and gave the network its highest rating in the time period since the 100th episode of “The Vampire Diaries” in January 2014.

Review: ‘DC’s Legends of Tomorrow’

By comparison, the premiere of “Arrow” on a Wednesday in October 2012 averaged a 1.3/4 in 18-49 and 4.14 million viewers overall, and “The Flash” in October 2014 opened with a monster 1.9/6 and 4.83 million. This week, “The Flash” did a 1.3, and “Arrow a 1.1.

And during the fall in the Thursday-at-hour for CW, “The Vampire Diaries” averaged a 0.6 in 18-49 and about 1.3 million total viewers, so last night’s premiere of “Legends” at least doubled the network’s fall average in most categories.

“Legends” was followed by the third-season premiere of “The 100” (0.7/2 in 18-49, 2.0 million viewers overall), which had its highest-rated episode since its second outing in March 2014. Overall, the CW has its most-watched Thursday in more than three years (since October 2012) and its highest-rated Thursday in 18-49 in more than two years (since November 2013).

Review: ‘The 100’ Season 3

At Fox, a two-hour “American Idol” averaged a timeslot-leading 2.4/8 in 18-49 and 9.3 million viewers overall from 8 to 10 p.m., up 0.2 from last week. It swept the time period in everything from kids 2-11 (1.2/5) and teens 12-17 (1.3/7) to adults 18-34 (1.7/7), 18-49 and 25-54 (3.1/8).

CBS opened the night with a repeat of “The Big Bang Theory” (2.2/8 in 18-49, 11.0 million viewers overall), followed by originals of “Life in Pieces” (2.0/6 in 18-49, 8.8 million viewers overall), “Mom” (1.7/5 in 18-49, 8.5 million viewers overall), “Angel From Hell” (1.4/4 in 18-49, 7.0 million viewers overall) and “Elementary” (1.1/4 in 18-49, 6.3 million viewers overall). “Life in Pieces” seems to have found its own audience, matching its week-ago average even with “Big Bang Theory” in repeat this time and placing a competitive second in its timeslot to “American Idol.” “Angel From Hell,” meanwhile, improved its chances of hanging around by increasing by a tenth week to week and improving its retention of “Mom” to 82.%

At NBC, the finale of “Heroes Reborn” (1.0/3 in 18-49, 3.8 million viewers overall) was unable to see any lift, matching last week’s rating. “Blacklist” (1.5/5 in 18-49, 7.3 million viewers overall) was down a tick, but “Shades of Blue” (1.4/5 in 18-49, 6.9 million viewers overall) bounced back from last week’s 28% week two falloff to win its hour among the broadcast networks for a third straight week. Last week’s episode saw a nice lift in delayed-viewing numbers, including a 3-day pickup of 3.75 million total viewers, down just a bit from 3.96 million for its premiere.

ABC fell to fifth among the English-language broadcasters last night with unscripted series “Beyond the Tank” (1.0/3 in 18-49, 4.3 million viewers overall) and “My Diet is Better Than Yours” (0.7/2 in 18-49, 2.3 million viewers overall), the latter of which was up slightly from last week (0.65 vs. 0.61). The net’s TGIT dramas “Grey’s Anatomy,” “Scandal” and “How to Get Away With Murder” return Feb. 11.