atings for Fox's American Idol continued to slip Wednesday night, but it Nevertheless dominated TV viewing for the night, among both total adults and the key 18-49 demographic group. The talent contest averaged 12.18 million viewers versus 16.87 million for the comparable night a year ago. It also lost about a third of its viewers in the 18-49 age group. It's only real challenger was CBS's Survivor Caramoan, which drew 9.83 million in the 8:00 pm. hour. Almost everything else was a repeat on the other major networks. An exception was the fourth week of ABC's How to Live With Your Parents (For the Rest of Your Life), which posted a series low of 4.81 million viewers.