Note J – Segment Information Note K - Earnings (Loss) Per Share Note L - Concentrations of Credit Risk Effective January 1, 2017, the Company determined that its business constituted one reportable property and casualty insurance segment based on how its operating results are regularly reviewed by the Company's chief operating decision maker when making decisions about how resources are allocated and assessing performance. The property and casualty insurance segment provides multiple lines of insurance coverage primarily to commercial automobile companies, as well as to independent contractors who contract with commercial automobile companies. The following table summarizes segment revenues for the years ended December 31: The following is a reconciliation of the denominators used in the calculation of basic and diluted earnings (loss) per share for the years ended December 31: The Company writes policies of excess insurance attaching above SIRs and also writes policies that contain per-claim deductibles. Those losses and claims that fall within the SIR limits are obligations of the insured; however, the Company writes surety bonds in favor of various regulatory agencies guaranteeing the insureds' payment of claims within the SIR. Further, specified portions of losses and claims incurred under large deductible policies, while obligations of the Company, are contractually reimbursable to the Company from the insureds. The Company requires collateral from its insureds to serve as a source of reimbursement if the Company is obligated to pay claims within the SIR by reason of an insured's default or if the insured fails to reimburse the Company for deductible amounts paid by the Company. Acceptable collateral may be provided in the form of letters of credit on Company-approved banks, Company-approved marketable securities or cash. At December 31, 2019, the Company held collateral in the aggregate amount of $328,559. The amount of collateral required of an insured is determined by the financial condition of the insured, the type of obligations guaranteed by the Company, estimated reserves for incurred losses within the SIR or deductible that have been reported to the insured or the Company, estimated incurred but not reported losses, and estimated losses that are expected to occur within the SIR or be deductible prior to the next collateral adjustment date. In general, the Company attempts to hold collateral equal to 100% of the ultimate losses that would be paid by or due the Company in the event of an insured's default. Periodic audits are conducted by the Company to evaluate its exposure and the collateral required. If a deficiency in collateral is noted as the result of an audit, additional collateral is requested immediately.  Because collateral amounts contain numerous estimates of the Company's exposure, are adjusted only periodically and are sometimes reduced based on the superior financial condition of the insured, the amount of collateral held by the Company at a given point in time may not be sufficient to fully reimburse the Company for all of its guarantees or amounts due in the event of an insured's default. In that regard, the Company is not fully collateralized for the guarantees made for, or the deductible amounts that may be due from, FedEx Corporation and certain of its subsidiaries and related entities ("FedEx"), and in the event of their default, such default may have a material adverse impact on the Company. The Company estimates its uncollateralized exposure related to FedEx to be as much as 79% (after-tax) of shareholders' equity at December 31, 2019. - 60 - 2019 2018 2017 Revenues: Net premiums earned $ 447,288 $ 432,880 $ 328,145 Net investment income 26,249 22,048 18,095 Net realized and unrealized gains (losses) on investments 12,889 (25,691 ) 19,686 Commissions and other income 9,171 9,932 5,308 Total revenues $ 495,597 $ 439,169 $ 371,234 2019 2018 2017 Average shares outstanding for basic earnings (loss) per share 14,520,815 14,964,812  15,065,216 Dilutive effect of share equivalents 99,118 – 42,220 Average shares outstanding for diluted earnings (loss) per share 14,619,933 14,964,812  15,107,436 The Company's balance sheet includes paid and estimated unpaid amounts recoverable from reinsurers under various agreements. These recoverables are only partially collateralized. The two largest amounts due from individual reinsurers, net of collateral and offsets, were $53,915 and $44,462 at December 31, 2019.