This is Begonia x hiemalis Betulia - one of the Elatior group of Begonia hybrids - which are produced in bulk in Holland and widely sold over here as short-lived summer bedding plants.

They are not winter hardy and won't tolerate temps much below 10°C. Although they technically are perennial plants they are almost always treated as annuals. You can try over-wintering indoors as a house-plant by withholding water and allowing the plant to rest for 6 weeks once new flowers are no longer being produced. Then cut all stems back to 2 or 3 leaf nodes, and watering again to encourage re-growth. Another alternative is to over-winter as new, young plants from leaf cuttings.