From someone with YYZ as home airport, not an expert wanna be from MSP
Upon arrival from DTW you will head to Canadian immigration to be processed.
Next you deal with baggage pick up and customs.
Upon exit from customs you need to head up to departure level and walk to US departure, at the other end of the terminal(T3).
If you already have a BP you line up for US preclear document check. You then use GE kiosk or regular kiosk.
Once you have cleared US CBP you then line up for flight security.
After that you are in the US departure holding area and head to your gate.