Is it normal to picture killing tourself?

So it's not that I'm depressed or anything, I'm actually doing really good. But lately I've been picturing different ways to kill my self.. Like I'll be eating dinner with my family and my dad will start yelling and I'm staring at my plate, and I imagine my self smashing my head into the plate. When ever I'm holding a knife I'll picture stabbing myself. I never cut, and I don't act upon the thoughts, because there not urges.. Just.. I ideas