I believe it is Hymenocallis littoralis as SongofJoy suggests because of the anther facing sideways and the leaves are wide at the base.
But then I looked up Hymenocallis caribaea as Jon mentioned and of course that makes sense also because the flower was about 10 - 12 inches in diameter and the leaves were very broad, about 2 - 2/12 inches wide.... hmmm
Maybe that answers the question.... it must be the Hymenocallis caribaea ‘tropical giant’
all for your investigating for me