Is $x^{q^n-1}-1$ where $q$ is a power of a prime $p$ irreducible over $F_{q^n}$?

Question

Here the tower of extension is $\Bbb F_p\subset \Bbb F_q\subset E$ where $E$ is an extension of degree $n$ over $\Bbb F_q$ and $q=p^r$ for some natural number $r$. I wonder if it is the fact that $x^{q^n-1}-1$ is irreducible over $\Bbb F_q$. If it is, could someone please give a proof? Or else if it is not irreducible, could someone give some explaination?

Thanks a lot!