With CBS’ “The Big Bang Theory” back in originals for the first time in three weeks, a pair of new series in Thursday’s opening hour — NBC’s “You, Me and the Apocalypse” and CW’s “DC’s Legends of Tomorrow” — fell off last night, while NBC’s 10 p.m. cop drama “Shades of Blue” dipped in its fifth week.

The night featured a Democratic debate on MSNBC, but the event didn’t make big enough ratings noise to meaningfully impact the evening’s entertainment programs. In Nielsen’s metered-market overnights, the Hillary Clinton-Bernie Sanders debate from New Hampshire averaged a 3.3 household rating — less than half what a Donald Trump-less Republican debate did one week earlier on Fox News Channel (8.4) and the lowest of this election cycle for either party.

Looking at the night’s broadcast programs, “The Big Bang Theory” (3.7 rating/13 share in adults 18-49, 15.2 million viewers overall) was in line with its prior result and towered over the rest of the Thursday field in every category; it wouldn’t be surprising to see it rise 0.2 in the finals. Television’s top-rated comedy was followed by “Life in Pieces” (2.3/8 in 18-49, 9.4 million viewers overall) and “Mom” (1.8/6 in 18-49, 8.0 million viewers overall), which were slightly above average, and “Angel From Hell” (1.4/4 in 18-49, 6.3 million viewers overall), which held steady. If “Life” can stay as high as a 2.2 in the finals, it would match the first-year show’s best result on Thursday to date and its second highest overall (behind only its series premiere on a Monday last fall).

Fox won another Thursday with a two-hour “American Idol” (2.2/7 in 18-49, 8.9 million viewers overall), which was down a tenth from last week. After opening with a 2.0 at 8 p.m., the music competition rose to a 2.3 at 8:30 and stayed there the rest of the way. The show will face its toughest competition of the season starting next week when ABC’s female-friendly dramas “Grey’s Anatomy” and “Scandal” return.

NBC’s “You, Me and the Apocalypse” (0.9/3 in 18-49, 3.6 million viewers overall) was down 25% (0.3) from its passable premiere score of last week, but “Big Bang Theory” couldn’t be totally to blame for its decline, as the show last night opened with a 0.9 at 8 p.m. opposite the CBS megahit and slid to a 0.8 at 8:30. “The Blacklist” held up well behind it (1.5/5 in 18-49, 6.5 million viewers overall), down just a tenth, and “Shades of Blue” (1.1/4 in 18-49, 5.6 million viewers overall) fell 0.2 to its lowest score to date (though at 1.150 in the prelims, it has a good chance to round up to a 1.2 in the finals).

“Shades” has been a big gainer in delayed viewing, with the most recent “live plus-7” results from Nielsen showing the drama doubling its same-day rating in 18-49 (1.3 to 2.6) and spiking by nearly 4.7 million total viewers (6.64 million to 11.32 million). Last week’s “Shades of Blue” added more than 750,000 full-episode views in six days on NBC.com and Hulu.

The conclusion of ABC’s two-night original movie “Madoff” (1.0/3 in 18-49, 6.7 million viewers overall) retained nearly all of its Wednesday averages. And an ABC News special following it at 10 p.m., “Madoff: After the Fall,” grew to a 1.2/4 in 18-49 and also drew 6.7 million total viewers — edging out NBC’s “Shades of Blue” in the demo and winning its hour in total viewers as well.

At CW, “DC’s Legends of Tomorrow” (0.9/3 in 18-49, 2.3 million viewers overall) dipped 0.2 from last week but this number still puts it among the network’s top tier of dramas, behind only “The Flash” and about on par with “Arrow.” It placed third among the broadcasters in men 18-34 (0.8/4) and adults 18-34 (0.7/3) and improved upon the network’s performance a year ago with “The Vampire Diaries” by 44% in total viewers and 29% in 18-49.

“The 100” (0.6/2 in 18-49, 1.6 million viewers overall) held steady in its third week, growing from last year’s “Reign” in the 9 p.m. hour by 65% in total viewers and 17% in adults 18-49. Skewing younger, it more than doubled last year’s 18-34 average (0.5 vs. 0.2).