As far as I know, KLM no longer flies between DTW and AMS, and all such KLM flights are actually NW-operated.
On the KLM web site for March 22 (random day), your options are:
NW 40/KL 6040 DTW 16.05 AMS 05.55+1
NW 68/KL 6068 DTW 17.20 AMS 06.55+1
NW 54/KL 6054 DTW 18.55 AMS 08.45+1
NW 48/KL6048 DTW 21.40 AMS 11.30+1