Detachment is, in my opinion, the art of loving everything and everyone but not caring about the who, what, when, where, why, or how.
In my personal practice of detachment, I can describe it as being a LOT like being severely depressed (you know, at that point where you don't care about ANYTHING), but completely happy. Blissfully so, even.
I have six children. For most of their lives I've felt like they were mine, they belonged to me. I started to realize that they were actually separate beings from me when I was forced to start giving them up (one due to divorce and two due to them moving out when they were grown) and none of us died. Now I accept that, even though I'm important to them, I'm not vital to them.
So I've gotten to a point now that I'm choosing to rid myself of belongings that I don't need and am only hanging onto for sentimental reasons. It's really been so freeing. The fewer things I "own", the less scared I am of losing things. The less scared I become, the more fulfilled and happy I am. It's truly amazing.