For 2×2 matrices $A = \begin{pmatrix} 2 & 1 \\ 0 & 3 \end{pmatrix}$, $B = \begin{pmatrix} 1 & -1 \\ 2 & 1 \end{pmatrix}$, and $C = \begin{pmatrix} -1 & 0 \\ 2 & 2 \end{pmatrix}$, compute $\det(ABC)$.