The return of The Voice took up two nights of primetime this week for NBC, now it’s American Idol’s (3.1/9) turn for Fox. To celebrate judge Mariah Carey’s birthday and with Smokey Robinson as mentor, Wednesday’s two-hour live performance show paid homage to the music of Detroit Motor City. But the show was down 14% from last week’s final numbers and down 11% from its March 20 fast nationals — hitting an all-time Wednesday low. Both numbers are relevant because Idol has a tendency to adjust more than most in final numbers. Idol was watched by 12.03 million viewers last night. Oh, in case you forgot: The Voice and Idol will go head-to-head at least once this season on May 8 when the NBC show has scheduled a one-hour episode. Fox still won Wednesday in total viewers and the adults 18-49 demo.

CBS had the other big reality veteran of the night in Survivor: Caramoan (2.4/7). One contestant was voted off the island, the eighth of the season, and the show dipped 8% from its March 20 show. The top TV network of the season so far filled out the rest of the night with encores of Criminal Minds (1.3/4) and CSI (1.3/4).

Wednesday also saw two season finales with ABC’s The Neighbors (1.5/5) and a double shot of NBC’s Whitney at 8 PM (1.0/3) and 8:30 (1.1/3). The ABC sci-fi sitcom saw its freshman season come to a close up 7% from last week. For Whitney, the first broadcast was even with last week’s series low, while the 8:30 PM improved 10% from last week’s original. The second season ended down distinctly from the 1.6/5 of its March 28, 2012 finale at 8 PM. Law & Order: SVU (1.7/5) was up a slight 6% over last week’s show as was Chicago Fire (1.8/5). Before Neighbors, ABC started the night with The Middle (1.8/6), which was down 14% from its last original two weeks ago to hit a season low.

At 9 PM, Modern Family (3.2/9) hit a three-year low, dropping 20% from its last original February 27, when it topped Idol in the demo for the first time. On the flip side, Suburgatory (1.9/5) was up 27% from last week’s series low. Nashville (1.5/4) ended the night for ABC with a 6% slip from its last new show four weeks ago. That’s a series low for the freshman drama.

The CW had new episodes of Arrow (0.8/3) and Supernatural (1.0/3). The former was down two tenths from last week, while the latter was flat with its March 20 show.