Southwest does fly to Detroit, and I used them for a trip last fall. I remember needing to cancel the outbound leg because of a family emergency. I hit “Cancel” on their website expecting a hassle, but the travel credit appeared right away. It made a stressful week a little easier. Whenever I need quick booking changes—or when I'm unsure which airport they serve—I just call their hotline ☎️. It’s consistently been the fastest way to get things handled on the spot.