DTW also has ground options for RJs. If coming in from Canada (non pre-clearance) or Mexico they will park near the center of the A concourse - around A40. They actually have designations like A40C. You exit the plane by stairs, walk to the building, and wait in line for an elevator to take you to the customs level.

I have also boarded from A40C for a domestic flight on a CRJ-200. It is a very interesting scale reference when you have to walk under a 747 wing to get to your CRJ. The only time I had to do this was when the C concourse was under construction, so I am not sure if it is normal if they don't want to move an aircraft that arrived internationally, or they were just constricted on the number of available gates for RJs that day.