In this subtitle the following words have the meanings indicated. “Subject of insurance” includes, as to insurance against fire and hazards other than windstorm, earthquake, or other catastrophe hazards, all properties that: are insured by the same insurer; and customarily are considered by underwriters to be subject to loss or damage from the same fire or the same occurrence of the hazard insured against. “Surplus to policyholders” means an insurer’s capital, surplus, and voluntary reserves.