Sec. 215. No insurance company other than life, whether foreign or domestic, shall retain any risk on any one subject of insurance in an amount exceeding twenty per centum of its net worth. For purposes of this section, the term "subject of insurance" shall include all properties or risks insured by the same insurer that customarily are considered by non-life company underwriters to be subject to loss or damage from the same occurrence of any hazard insured against.
Reinsurance ceded as authorized under the succeeding title shall be deducted in determining the risk retained. As to surety risk, deduction shall also be made of the amount assumed by any other company authorized to transact surety business and the value of any security mortgage, pledged, or held subject to the surety's control and for the surety's protection.