I've seen some domestic FC P fares that are fully refundable (with no fees charged) and other P fares that are nonrefundable, sometimes for the same city pair. OP should be very careful.

I second the advice to be sure to print the fare rules, both the summary and the detailed rules that you get by clicking again on the fare code. If there's more than one fare code for the ticket (unlikely since it will be one way, but DL can show broken fares without warning the customer), do this for every fare code you see. Remember that (unlike some other airlines) delta.dumb does not have a way to see the fare rules after tickets have been purchased.