Ratings: Big Bang and Person of Interest Hit All-Time Highs, 30 Rock Falls Below Community

The Big Bang Theory continues to get bigger and bigger.

The CBS megahitcom this week drew an all-time Thursday high* of 16.4 million total viewers while scoring a 5.4 demo rating. In head-to-head competition for that first half-hour, the geeks bested American Idol (15.8/5.0) in both measures for a second consecutive week, and netted a win over the Fox juggernaut in the demo for a third straight time.

*UPDATE: Per the final ratings, Big Bang drew 16.54 million total viewers — aka the show’s unqualified largest audience ever.

For the full hour, American Idol drew 17.1 million total viewers and a 5.4 rating virtually flat with a week ago. The Finder led out of that with 7 mil and a 2.4, down 17 and 14 percent.

The Eye network eyed another high courtesy of Person of Interest, which hit new series bests in both total audience (with 15 million viewers, up 4 percent) and in the demo (up a tenth to 3.3).

A few other notes:

* As NBC comedies go, 30 Rock (3.2 mil/1.3) plunged 16 and 19 percent — falling below Community‘s most recent 3.62/1.5, ahemParks and Rec (3.65 mil/1.8) inched up 4 and 6 percent, The Office (5.3 mil/2.7) dropped double digits and Up All Night (3.8 mil/1.8) dipped 5 percent.

* Grey’s Anatomy‘s alt episode drew 9.64 million total viewers and a 3.5 rating, adding a few more eyeballs while flat in the demo. Private Practice (6.65 mil/2.3) gained 10 percent.

* The Vampire Diaries (2.7 mil/1.2) added a tenth in the demo, while The Secret Circle (1.7 mil/0.7) saw a 7 percent bump in total audience.

More to come, around 1 pm EST….