In this chapter, "health insurer" means an insurance company authorized to provide a hospital, surgical, and medical expense insurance plan in this state, including:
(1) a stock insurance company;
(2) a reciprocal or interinsurance exchange;
(3) a Lloyd's plan;
(4) a fraternal benefit society;
(5) a stipulated premium company; and
(6) a mutual insurance company, including a statewide mutual assessment company or a local mutual aid association.