You're right, the database only shows domestic.

However, in looking at DTW operations on 9/14/10, there is only one 777-200ER that operated as a domestic flight - it arrived from ATL as DL1005.

I then used flightstats.com for historical flight info (registration required, but free) to see arrival/departure gate to verify it was the same aircraft:
DL1005 arrived at A54 at 10:33
DL159 departed DTW at A54 at 12:36
N866DA

Same exercise for the return:
DL158 arrived at A56 at 18:04
DL1013 departed A56 at 19:32
N863DA

I think it was luck in this case that the ICN aircraft rotated through DTW to ATL. There were other 777 flights from DTW to PVG and HKG that would have been a lot harder to track as they didn't do a domestic rotation from DTW.