This is probably a dumb question, but it's my first trip, and searching for "San Juan" didn't do me a whole lot of good (e.g. I already know SJC is domestic )

Is SJU considered a domestic or an international destination? I have a flight DTW-SJU tomorrow, and I'm trying to figure out how early I need to arrive at DTW. From poking around NWA's site, it looks like there's no IFE, so that tips me toward thinking it's treated as a domestic flight.