# Turing decider Halting Problem

Wiki and my classes Textbook defines a decider as:

In computability theory, a machine that always halts—also called a decider (Sipser, 1996) or a total Turing machine (Kozen, 1997)—is a Turing machine that halts for every input.

So shouldn't this decider be able to decide the Halting Problem? Because it halts always? I am a bit confused.

On input $w$, accept if $|w|$ is even, and reject if $|w|$ is odd.