"Protected computer" is an incredibly broad term that covers almost any modern computer or device:

(2) the term “protected computer” means a computer— ... (B) which is used in or affecting interstate or foreign commerce or communication, including a computer located outside the United States that is used in a manner that affects interstate or foreign commerce or communication of the United States;

I can't imagine they'd ever prosecute anything below the $5,000 mark but even a candy bar sized loss does appear to fall into the federal domain. (Not saying I agree with it, but that's how the interstate commerce clause has been applied in almost every case.)