CBS rolled to a comfortable prime-time ratings win Thursday night, based on Nielsen overnights for the key 18-49 demo, as NBC — once the ruler of Thursday nights with its Must-See TV lineup — struggled to a fifth-place finish among the broadcast networks.

TVbytheNumbers.com reports that CBS's "The Big Bang Theory" was the top show on broadcast prime by a wide margin, even as the sitcom equaled its season low in the 18-49 demo. "Bang" dipped 2% from its most recent episode to a 4.8 average, while also delivering a whopping 17.4 million total viewers.

The rest of the CBS lineup was mostly up: "The Millers" rose 21% from its most recent episode in viewers 18-49 to a 2.9 average to rank No. 2 on broadcast prime behind only "Big Bang." "Two and a Half Men" ticked up 4% to a 2.5, and "The Crazy Ones" climbed 6% to a 1.8. "Elementary," however, headed in the other direction — down 6% to a 1.6.

NBC was mostly down, with "Community" plunging 18% from its most recent installment to register a 0.9 average in 18-49, the show's all-time low mark. "Parks and Recreation" was off 8% with a 1.1 average, and "Parenthood" lost 14% to settle for a 1.2. Defying the network's downtrend was "Hollywood Game Night," which rose 10% to a 1.1.

Fox saw its onetime ratings juggernaut "American Idol" continue to erode. In its half-hour format, the singing competition slipped 5% from last week to a 1.8 average rating in the 18-49 demo, the show's all-time low.

The rest of the Fox lineup also headed downward. "Hell's Kitchen" was off 11% from last week with a 1.7 in 18-49, and "Surviving Jack" slipped 8% to a 1.2.

ABC aired the series finale of "Once Upon a Time in Wonderland," which was down 10% from a week ago with a 0.9 average in adults 18-49. "Scandal" also fell 10%, equaling its season low with a 2.8 average — still the highest-rated series of the night not on CBS. "Grey's Anatomy" held steady with a respectable 2.6.

For prime time overall, CBS coasted to a win in the 18-49 demo with a 2.5 average, ahead of ABC (2.1 average), Fox (1.6), Univision (1.2) and NBC (1.1). CBS finished well ahead of the others in total viewers, averaging 10.0 million to lead ABC (6.7 million), Fox (5.5 million), NBC (3.2 million) and Univision (2.8 million).

The report notes that the numbers for all networks may be subject to more than the usual adjustments due to weather-related pre-emptions in several markets.