If it is really true that we could go back in time and act as you stated, then i would say it suggests that there is no need for a "first step" in any chain of events. One could simply loop. In your example, no one would ever really have created the document, it would be just a loop consisting of sending it to the past, receiving it, and sending it to your past self. Your past self never created it, because you received it from your future self, and your future self never created it, because it also received it in past times.
As i understand it, that is a really complicated question. We should not say that time travel (from and to the same universe) is impossible because that would generate an inconsistent universe: It doesn't seem correct to use the consequences of an idea to disprove it. However, it does look like we live in a consistent world. My guess is that this is an argument against time travels: if, somewhere in the future, we achieved them (i mean, the ones that happen from and to the same universe), our present would not look that consistent. Conclusion: time travels must be impossible, because the universe is consistent.