Random walk on a square to the opposite corner

Four corners of a square are labeled $A, B, C, D$ in order around the edge, so the neighbors of $A$ are $B$ and $D$, and $C$ is the corner diagonally opposite $A$. A token sits at $A$. Each step it moves to one of the two adjacent corners, each with probability $\tfrac12$. It stops on reaching $C$.

What is the expected number of steps for the token to reach $C$?