What if this package had been stolen or ruined?

My dad just ordered a 3,000 dollar gibson guitar, and it was supposed to show up sometime yesterday afternoon. I had to wait around at my house all day because it was supposed to have a signature to be delivered. It didnt come all day and once my mom got home we waited about another hour until six-thirty and umed it wouldnt be coming that day, so we went to get groceries. But then when we came home it was sitting on our doorstep. That would have been fine for most packages, but my question is, if it had been stolen or ruined by rain (which it almost did rain, by the way) would it have been UPS's fault, or would we be the ones responsible for replacing it? Keep in mind that we arent a rich family and dont just have 3,000 dollars to throw away, but my dad has been saving up for this specific guitar for years.