Sorry I missed this. Here in Indiana it is way too cold to leave them outside I have found. So here is what I do. Wait until the frost kills them back. Cut off all the dead limbs and leaves all the way back to the bulb. Throw the bulbs in to 5 gallon buckets. I have an attached, unheated garage. It stays cold throughout the winter but does not freeze. I just throw the buckets into a dark place in the garage until spring. The bulbs dry out and stay dormant until the warmth returns. So do not do anything fancy. Don't let them freeze.
If you have room for them, do as the Doc says. They are nice tropical looking plants. But since I have several large ones, bulbs half the size of your head, I just let them go dormant for the winter.