a combination of bad luck, inattention and concentration loss; we've all done it. of course, this doesn't make it any easier. don't you hate that "crunching " sound, even before you inspect the damage, you know it is going to cost $$$. no, you are not an idiot, but we all feel pretty stupid after an incident like this. I know I did!!!. the good part of your story is that nobody was injured. good luck with the upcoming repairs.