Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

The accompanying consolidated financial statements (“Financial Statements”) include the accounts of the Parent and its subsidiaries, and have been prepared in conformity with: (i) U.S. generally accepted accounting principles ("GAAP"); and (ii) the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation.

Use of Estimates

The preparation of our Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported financial statement balances, as well as the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Reclassifications

In 2017, we reclassified certain line items within our Consolidated Statements of Income to enhance the ability to analyze our expenses. Specifically, we reclassified our insurance underwriting expenses into amortization of deferred policy acquisition costs and other insurance expenses. These expenses were previously included in policy acquisition costs and other expenses. In addition, all expenses of the Parent, which were previously included in other expenses, are now separately identifiable as corporate expenses on the Consolidated Statements of Income. All prior periods presented in this Form 10-K have been reclassified to reflect this change.

Investments

Fixed income securities may include investment grade and below investment grade rated bonds, redeemable preferred stocks, non-redeemable preferred stocks with certain debt-like characteristics, mortgage-backed securities (“MBS”), collateralized loan obligations ("CLO"), and other asset-backed securities (“ABS”). MBS, CLO, and other ABS are jointly referred to as structured securities. Fixed income securities classified as available-for-sale (“AFS”) are reported at fair value. Those fixed income securities that we have the ability and positive intent to hold to maturity are classified as held-to-maturity (“HTM”) and are carried at either: (i) amortized cost; or (ii) market value at the date of transfer into the HTM category, adjusted for subsequent amortization. The amortized cost of fixed income securities is adjusted for the amortization of premiums and the accretion of discounts over the expected life of the security using the effective yield method. Premiums and discounts arising from the purchase of structured securities are amortized over the expected life of the security based on future principal payments, giving additional consideration to prepayments. These prepayments are estimated based on historical and projected cash flows. Prepayment assumptions are reviewed quarterly and adjusted to reflect actual prepayments and changes in expectations. Future amortization of any premium and/or discount is adjusted to reflect the revised assumptions. Interest income, as well as amortization and accretion, is included in "Net investment income earned" on our Consolidated Statements of Income. The amortized cost of a fixed income security is written down to fair value when a decline in value is considered to be other than temporary. See the discussion below on realized investment gains and losses for a description of the accounting for impairments. After-tax unrealized gains and losses on: (i) fixed income securities classified as AFS; and (ii) fixed income securities that were transferred into an HTM designation from an AFS designation, are included in accumulated other comprehensive income (loss) ("AOCI").

Equity securities, which are classified as AFS, may include common and non-redeemable preferred stocks. These securities are carried at fair value and the related dividend income is included in "Net investment income earned" on our Consolidated Statements of Income. The cost of equity securities is written down to fair value when a decline in value is considered to be other than temporary. See the discussion below on realized investment gains and losses for a description of the accounting for impairments. After-tax unrealized gains and losses are included in AOCI.

Short-term investments may include certain money market instruments, savings accounts, commercial paper, and debt issues purchased with a maturity of less than one year. We also enter into reverse repurchase agreements that are included in short-term investments. These loans are fully collateralized with high quality, readily marketable instruments at a minimum of 102% of the loan principal. At maturity, we receive principal and interest income on these agreements. All short-term investments are carried at cost, which approximates fair value. The associated income is included in "Net investment income earned" on our Consolidated Statements of Income.

Other investments may include alternative investments and other securities. Alternative investments are accounted for using the equity method. Our share of distributed and undistributed net income from alternative investments is included in "Net investment income earned" on our Consolidated Statements of Income. Other securities are primarily comprised of tax credit investments. Low income housing tax credits are accounted for under the proportional amortization method and all other tax credits are accounted for using the equity method. Under the proportional amortization method, our share of the investment’s performance is recorded in our Consolidated Statements of Income as a component of “Federal income tax expense.” Under the equity method, our share of distributed and undistributed net income is included in "Net investment income earned" on our Consolidated Statements of Income. For federal income tax credits accounted for under the equity method, we use the deferral method for recognizing the benefit of the tax credit with the related deferred revenue being recognized in our Consolidated Statements of Income as a component of "Federal income tax expense" proportionately over the life of the investment.

We evaluate the alternative investments and tax credit investments included in our other investments portfolio to determine whether those investments are variable interest entities ("VIEs") and if so, whether consolidation is required. A VIE is an entity that either has equity investors that lack certain essential characteristics of a controlling financial interest or lack sufficient funds to finance its own activities without financial support provided by other entities. We consider several significant factors in determining if our investments are VIEs and if we are the primary beneficiary, including whether we have: (i) the power to direct activities of the VIE; (ii) the ability to remove the decision maker of the VIE; (iii) the ability to participate in making decisions that are significant to the VIE; and (iv) the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIE. We have reviewed our alternative and tax credit investments and have concluded that they are VIEs, but that we are not the primary beneficiary and therefore, consolidation is not required.

Realized gains and losses on the sale of investments are determined on the basis of the cost of the specific investments sold and are credited or charged to income. Included in realized gains and losses are the other-than-temporary impairment ("OTTI") charges recognized in earnings, which are discussed below.

On a quarterly basis, we review our investment portfolio for impairments that are other than temporary. Interest-related unrealized losses typically do not result in other-than-temporary impairments. The following provides information on this analysis for our fixed income securities and short-term investments, equity securities, and other investments.

Fixed Income Securities and Short-Term Investments

We review securities that are in an unrealized loss position to determine: (i) if we have the intent to sell the security; (ii) if it is more likely than not that we will be required to sell the debt security before its anticipated recovery; and (iii) if the decline is other than temporary. Broad changes in the overall market or interest rate environment generally will not lead to a write down. If we determine that we have either the intent or requirement to sell the security, we write down its amortized cost to its fair value through a charge to earnings as a component of realized losses. If we do not have either the intent or requirement to sell the security, our evaluation for OTTI may include, but is not limited to, evaluation of the following factors:


•	Whether the decline appears to be issuer or industry specific;


•	The degree to which the issuer is current or in arrears in making principal and interest payments on the fixed income security;


•	The issuer’s current financial condition and ability to make future scheduled principal and interest payments on a timely basis;


•	Evaluation of projected cash flows;


•	Buy/hold/sell recommendations published by outside investment advisors and analysts; and


•	Relevant rating history, analysis, and guidance provided by rating agencies and analysts.

Non-redeemable preferred stocks that are classified as fixed income securities are evaluated under this OTTI method unless the security is below investment grade, at which time it is evaluated under the equity securities OTTI model discussed below.

To determine if an impairment is other than temporary, we perform assessments that may include, but are not limited to, a discounted cash flow analysis ("DCF") to determine the security's present value of future cash flows. This analysis is also performed on all previously-impaired debt securities that continue to be held by us and all structured securities that were not of high credit quality at the date of purchase. Any shortfall in the expected present value of the future cash flows, based on the DCF, from the amortized cost basis of a security is considered a “credit impairment,” with the remaining decline in fair value of a security considered a “non-credit impairment.” Credit impairments are charged to earnings as a component of realized losses, while non-credit impairments are recorded to Other Comprehensive Income ("OCI") as a component of unrealized losses.

The discount rate we use in a DCF is the effective interest rate implicit in the security at the date of acquisition for those structured securities that were not of high credit quality at acquisition. For all other securities, we use a discount rate that equals the current yield, excluding the impact of previous OTTI charges, used to accrete the beneficial interest. DCFs may include, but are not necessarily limited to: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as the historical performance of the underlying collateral, including net operating income generated by underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers.

Equity Securities

We review securities that are in an unrealized loss position to determine: (i) if we do not intend to hold the security to its forecasted recovery; or (ii) if the decline is other than temporary, which includes declines driven by market volatility for which we cannot assert the security will recover in the near term. If we determine either that we do not intend to hold a security, or the decline is other than temporary, we write down the security's cost to its fair value through a charge to earnings as a component of realized losses. If we intend to hold the security, our evaluation for OTTI may include, but is not limited to, an evaluation of the following factors:


•	Whether the decline appears to be issuer or industry specific;


•	The relationship of market prices per share to book value per share at the date of acquisition and date of evaluation;


•	The price-earnings ratio at the time of acquisition and date of evaluation;


•	The financial condition and near-term prospects of the issuer, including any specific events that may influence the issuer's operations, coupled with our intention to hold the securities in the near-term;


•	The recent income or loss of the issuer;


•	The independent auditors' report on the issuer's recent financial statements;


•	The dividend policy of the issuer at the date of acquisition and the date of evaluation;


•	Buy/hold/sell recommendations or price projections published by outside investment advisors;


•	Rating agency announcements;


•	The length of time and the extent to which the fair value has been, or is expected to be, less than its cost in the near term; and


•	Our expectation of when the cost of the security will be recovered.

Other Investments

Our evaluation for OTTI of an other investment (i.e., an alternative investment) may include, but is not limited to, conversations with the management of the alternative investment concerning the following:


•	The current investment strategy;


•	Changes made or future changes to be made to the investment strategy;


•	Emerging issues that may affect the success of the strategy; and


•	The appropriateness of the valuation methodology used regarding the underlying investments.

If there is a decline in the fair value of an other investment that we do not intend to hold, or if we determine the decline is other than temporary, we write down the carry value of the investment and record the charge through earnings as a component of realized losses.

Fair Value of Financial Instruments

Fair Values of Financial Instruments

Assets

The fair values of our investments are generated using various valuation techniques and are placed into the fair value hierarchy considering the following: (i) the highest priority is given to quoted prices in active markets for identical assets (Level 1); (ii) the next highest priority is given to quoted prices in markets that are not active or inputs that are observable either directly or indirectly, including quoted prices for similar assets in markets that are not active and other inputs that can be derived principally from, or corroborated by, observable market data for substantially the full term of the assets (Level 2); and (iii) the lowest priority is given to unobservable inputs supported by little or no market activity and that reflect our assumptions about the exit price, including assumptions that market participants would use in pricing the asset (Level 3). An asset’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. Transfers between levels in the fair value hierarchy are recognized at the end of the reporting period.

The techniques used to value our financial assets are as follows:

Level 1 Pricing



Security Type	Methodology
Equity Securities; U.S. Treasury Notes	Equity and U.S. Treasury Note prices are received from an independent pricing service that are based on observable market transactions. We validate these prices against a second external pricing service, and if established market value comparison thresholds are breached, further analysis is performed to determine the price to be used.
Short-Term Investments	Short-term investments are carried at cost, which approximates fair value. Given the liquid nature of our short-term investments, we generally validate their fair value by way of active trades within approximately one week of the financial statement close.

Level 2 Pricing

We utilize a market approach for our Level 2 securities, using primarily matrix pricing models prepared by external pricing services. Matrix pricing models use mathematical techniques to value debt securities by relying on the securities' relationship to other benchmark quoted securities, and not relying exclusively on quoted prices for specific securities, as the specific securities are not always frequently traded. As a matter of policy, we consistently use one pricing service as our primary source and secondary pricing services if prices are not available from the primary pricing service. Fixed income securities portfolio pricing is reviewed for reasonableness in the following ways: (i) comparing our pricing to other third-party pricing services as well as benchmark indexed pricing; (ii) comparing fair value fluctuations between months for reasonableness; and (iii) reviewing stale prices. If further analysis is needed, a challenge is sent to the pricing service for review and confirmation of the price.

Further information on our Level 2 asset pricing is included in the following table:



Security Type	Methodology
Corporate Securities including preferred stocks classified as Fixed Income Securities, and U.S. Government and Government Agencies	Evaluations include obtaining relevant trade data, benchmark quotes and spreads and incorporating this information into either spread-based or price-based evaluations as determined by the observed market data. Spread-based evaluations include: (i) creating a range of spreads for relevant maturities of each issuer based on the new issue market, secondary trading, and dealer quotes; and (ii) incorporating option adjusted spreads for issues that have early redemption features. Based on the findings in (i) and (ii) above, final spreads are derived and added to benchmark curves. Price-based evaluations include matching each issue to its best-known market maker and contacting firms that transact in these securities.
Obligations of States and Political Subdivisions	Evaluations are based on yield curves that are developed based on factors such as: (i) benchmarks to issues with interest rates near prevailing market rates; (ii) established trading spreads over widely-accepted market benchmarks; (iii) yields on new issues; and (iv) market information from third-party sources such as reportable trades, broker-dealers, or issuers.
Structured Securities (including CLO and other ABS, Commercial Mortgage-Backed Securities ("CMBS"), Residential Mortgage-Backed Securities ("RMBS"))	Evaluations are based on a DCF, including: (i) generating cash flows for each tranche considering tranche-specific data, market data, and other pertinent information, such as historical performance of the underlying collateral, including net operating income generated by the underlying properties, conditional default rate assumptions, loan loss severity assumptions, consensus projections, prepayment projections, and actual pool and loan level collateral information; (ii) identifying applicable benchmark yields; and (iii) applying market-based tranche-specific spreads to determine an appropriate yield by incorporating collateral performance, tranche-level attributes, trades, bids, and offers.
Foreign Government	Evaluations are performed using a DCF model and by incorporating observed market yields of benchmarks as inputs, adjusting for varied maturities.

Level 3 Pricing

Less than 1% of our portfolio cannot be priced using our primary or secondary pricing service. At times, we may use non-binding broker quotes to value some of these securities. These prices are from various broker/dealers that use bid or ask prices, or benchmarks to indices, in measuring the fair value of a security. We review these fair value measurements for reasonableness. This review typically includes an analysis of price fluctuations between months with variances over established thresholds being analyzed further.

Further information on our current Level 3 asset pricing is included in the following table:



Security Type	Methodology
Corporate Securities	These tax credit investments are priced internally using spread-based evaluations.
Equity Securities	These non-publicly traded stocks are valued by the issuer and reviewed internally.

Liabilities

The techniques used to value our notes payable are as follows:

Level 1 Pricing



Security Type	Methodology
5.875% Senior Notes	Based on the quoted market prices.

Level 2 Pricing



Security Type	Methodology
7.25% Senior Notes; 6.70% Senior Notes	Based on matrix pricing models prepared by external pricing services.
Borrowings from Federal Home Loan Banks	Evaluations are performed using a DCF model based on current borrowing rates provided by the Federal Home Loan Banks that are consistent with the remaining term of the borrowing.

See Note 7. “Fair Value Measurements” for a summary table of the fair value and related carrying amounts of financial instruments.

Allowance for Doubtful Accounts

We estimate an allowance for doubtful accounts on our premiums receivable. This allowance is based on historical write-off percentages adjusted for the effects of current and anticipated trends. An account is charged off when we believe it is probable that we will not collect a receivable. In making this determination, we consider information obtained from our efforts to collect amounts due directly or through collection agencies.

Share-Based Compensation

Share-based compensation consists of all share-based payment transactions in which an entity acquires goods or services by issuing (or offering to issue) its shares, share units, share options, or other equity instruments. The cost resulting from all share-based payment transactions are recognized in the Financial Statements based on the fair value of both equity and liability awards. The fair value is measured at grant date for equity awards, whereas the fair value for liability awards are remeasured at each reporting period. The fair value of both equity and liability awards is recognized over the requisite service period. The requisite service period is typically the lesser of the vesting period or the period of time from the grant date to the date of retirement eligibility. The expense recognized for share-based awards, which, in some cases, contain performance criteria, is based on the number of shares or units expected to be issued at the end of the performance period. We repurchase the Parent’s stock from our employees in connection with tax withholding obligations, as permitted under our stock-based compensation plans. This activity is disclosed in our Consolidated Statements of Stockholders' Equity.

Reinsurance

Reinsurance recoverables represent estimates of amounts that will be recovered from reinsurers under our various treaties. Generally, amounts recoverable from reinsurers are recognized as assets at the same time and in a manner consistent with the paid and unpaid losses associated with the reinsured policies. We require collateral to secure reinsurance recoverables primarily from our reinsurance carriers that are not authorized, otherwise approved, or certified to do business in one or more of our ten insurance subsidiaries' domiciliary states. Our ten insurance subsidiaries are collectively referred to as the "Insurance Subsidiaries." This collateral is typically in the form of a letter of credit or cash. An allowance for estimated uncollectible reinsurance is recorded based on an evaluation of balances due from reinsurers and other available information, such as each reinsurers' credit rating from A.M. Best Company ("A.M. Best") or Standard & Poor's Rating Services ("S&P"). We charge off reinsurance recoverables on paid losses when it becomes probable that we will not collect the balance.

Property and Equipment

Property and equipment used in operations, including certain costs incurred to develop or obtain computer software for internal use, are capitalized and carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. The following estimated useful lives can be considered as general guidelines:



Asset Category		Years
Computer hardware		3
Computer software		3 to 5
Internally developed software		5 to 10
Software licenses		3 to 5
Furniture and fixtures		10
Buildings and improvements		5 to 40

We recorded depreciation expense of $17.8 million, $17.4 million, and $16.4 million for 2017, 2016, and 2015, respectively.

Deferred Policy Acquisition Costs

Deferred policy acquisition costs are limited to costs directly related to the successful acquisition of insurance contracts. Costs meeting this definition typically include, among other things, sales commissions paid to our distribution partners, premium taxes, and the portion of employee salaries and benefits directly related to time spent on acquired contracts. These costs are deferred and amortized over the life of the contracts.

Accounting guidance requires a premium deficiency analysis to be performed at the level an entity acquires, services, and measures the profitability of its insurance contracts. We currently perform three premium deficiency analyses for our insurance operations, consistent with our reportable segments of Standard Commercial Lines, Standard Personal Lines, and E&S Lines. A combined ratio of over 100% does not necessarily indicate a premium deficiency, as any year's combined ratio includes a portion of underwriting expenses that are expensed at policy inception and therefore are not covered by the remaining unearned premium. In addition, investment income is not contemplated in the combined ratio calculation.

There were no premium deficiencies for any of the reported years, as the sum of the anticipated loss and loss expense, unamortized acquisition costs, policyholder dividends, and other expenses for each segment did not exceed that segment’s related unearned premium and anticipated investment income. The investment yields assumed in the premium deficiency assessment for each reporting period, which were based on our actual average investment yield before tax as of the September 30 calculation date, were 2.9% for 2017, 2.4% for 2016, and 2.5% for 2015.

Goodwill

Goodwill results from business acquisitions where the cost of assets and liabilities acquired exceeds the fair value of those assets and liabilities. A quantitative goodwill impairment analysis is performed if our quarterly qualitative analysis indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. Goodwill is allocated to the reporting units for purposes of these analyses. Based on our analysis at December 31, 2017, goodwill was not impaired.

Reserve for Loss and Loss Expense

Reserves for Loss and Loss Expense

Reserves for loss and loss expense are comprised of both case reserves on individual claims and reserves for claims incurred but not reported ("IBNR"). Case reserves result from claims that have been reported to one or more of our Insurance Subsidiaries, and are estimated at the amount of the expected ultimate payment. IBNR reserves are established at more aggregated levels than case basis reserves, and in addition to reserves on claims that have been incurred but not reported, they include provisions for future emergence on known claims, as well as reopened claims. IBNR reserves are established based on the results of the Insurance Subsidiaries’ internal reserve analysis, supplemented with other internal and external information.

The internal reserve analysis is performed quarterly, and relies upon generally accepted actuarial techniques. Such techniques assume that past experience, adjusted for the effects of current developments and anticipated trends, are an appropriate basis for predicting future events. Our analyses rely upon historical paid and case loss and loss expense experience organized by line of business, accident year, and maturity (i.e., “triangles”). Standard actuarial projection methods are applied to this history, producing a set of estimated ultimate loss and loss expenses. Ultimate loss and loss expenses are selected from the various methods, considering the strengths and weaknesses of the methods as they apply to the specific line and accident year.

Certain types of exposures do not lend themselves to standard actuarial methods. Examples of these are:

•

Certain property catastrophe events may be low in frequency and high in severity. These events may affect many insureds simultaneously. Due to the unique nature of these events, ultimate liabilities are estimated for each event, based on surveys of our portfolio of exposures, in conjunction with individual claims estimates. While generally short-tailed, the liabilities associated with these events are subject to a higher degree of uncertainty. We maintain significant reinsurance protection that greatly limits the impact that these extreme events have on net loss and loss expenses.

•

Some insured events may span multiple years and trigger multiple policies, as in the case of asbestos and environmental claims, where the injury is deemed to occur over an extended period of time. These types of losses often do not lend themselves to traditional actuarial methods. Where we deem appropriate, our experience may be analyzed without differentiating by accident year, using alternative methods and metrics. In these cases, the associated selected ultimate loss and loss expenses are then allocated to the applicable accident years for reporting.


•	Another example of non-standard methods relate to loss expenses that cannot be attributed to a specific claim (referred to as “unallocated loss expenses”). These expenses are first allocated to line of business, and alternative projection methods are then applied to estimate expenses by calendar year, which are then allocated back to the applicable accident years for reporting.

The selected ultimate losses and loss adjustment expenses are translated into indicated IBNR reserves, which are then compared to the recorded IBNR reserves. Management's judgment is applied in determining any required adjustments and the resulting adjustments are then recorded and assigned or allocated to accident year using the results of the actuarial analysis.

While the reserve analysis is the primary basis for determining the recorded IBNR reserves, other internal and external factors are considered. Internal factors include: (i) supplemental data regarding claims reporting and settlement trends; (ii) exposure estimates for reported claims, along with recent development on those estimates with respect to individual large claims and the aggregate of all claims; (iii) the rate at which new large or complex claims are being reported; and (iv) additional trends observed by claims personnel or reported to them by defense counsel. External factors considered include: (i) legislative enactments; (ii) judicial decisions; (iii) legal developments in the determination of liability and the imposition of damages; and (iv) trends in general economic conditions, including the effects of inflation.

Loss reserves are estimates, and as such, we also consider a range of possible loss and loss expense reserve estimates. This range is determined at the beginning of each year, using prior year-end data, and reflects the fact that there is no single precise method for estimating the required reserves, due to the many factors that may influence the amounts ultimately paid. Considering the reserve range along with all of the items described above, as well as current market conditions, IBNR estimates are then established and recorded.

The combination of the IBNR estimates along with the case reserve estimates on individual claims results in our total reserves for loss and loss expense. These reserves are expected to be sufficient for settling losses and loss reserve obligations under our policies on unpaid claims, including changes in the volume of business written, claims frequency and severity, the mix of business, claims processing, and other items that management expects to affect our ultimate settlement of loss and loss expense. However, the ultimate claim settlements may be higher or lower than reserves established. As our experience emerges and other information develops, we revise our reserve estimates accordingly. The changes in these estimates, resulting from the continuous review process and the differences between estimates and ultimate payments, are reflected in the Consolidated Statements of Income for the period in which such estimates are changed. The associated impacts may be material to the results of operations in future periods.

We do not discount to present value that portion of our losses and loss expense reserves expected to be paid in future periods.

Our loss and loss expense reserves implicitly include anticipated recoveries for salvage and subrogation claims.

Claims are counted at the occurrence, line of business, and policy level. For example, if a single occurrence (e.g. an auto accident) leads to a claim under an auto and an associated umbrella policy, they are each counted separately. Conversely, multiple claimants under the same occurrence/line/policy would contribute only a single count. The claim counts provided are on a reported basis. A claim is considered reported when a reserve is established or payment is made. Therefore, claims closed without payment are included in the count as long as there was an associated case reserve at some point in its life cycle.

We also write a small amount of assumed reinsurance. Currently, this business is limited to our share of certain involuntary pools. Since the associated claims are not processed by us, they are not captured within our claims system. Therefore, the claim counts reported exclude this business.

Revenue Recognition

The Insurance Subsidiaries' net premiums written (“NPW”) include direct insurance policy writings, plus reinsurance assumed and estimates of premiums earned but unbilled on the workers compensation and general liability lines of insurance, less reinsurance ceded. The estimated premium on the workers compensation and general liability lines is referred to as audit premium. We estimate this premium, as it is anticipated to be either billed or returned on policies subsequent to expiration based on exposure levels (i.e. payroll or sales). Audit premium is based on historical trends adjusted for the uncertainty of future economic conditions. Economic instability could ultimately impact our estimates and assumptions, and changes in our estimate may be material to the results of operations in future periods. Premiums written are recognized as revenue over the period that coverage is provided using the semi-monthly pro-rata method. Unearned premiums and prepaid reinsurance premiums represent that portion of premiums written that are applicable to the unexpired terms of policies in force.

Dividends to Policyholders

We establish reserves for dividends to policyholders on certain policies, most significantly workers compensation policies. These dividends are based on the policyholders' loss experience. Dividend reserves are established based on past experience, adjusted for the effects of current developments and anticipated trends. The expense for these dividends is recognized over a period that begins at policy inception and ends with the payment of the dividend. We do not issue policies that entitle the policyholder to participate in the earnings or surplus of our Insurance Subsidiaries.

Federal Income Tax

We use the asset and liability method of accounting for income taxes. Current federal income taxes are recognized for the estimated taxes payable or refundable on tax returns for the current year. Deferred federal income taxes arise from the recognition of temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities. We consider all evidence, both positive and negative, with respect to our federal tax loss carryback availability, expected levels of pre-tax financial statement income, and federal taxable income, when evaluating whether the temporary differences will be realized. In projecting future taxable income, we begin with budgeted pre-tax income adjusted for estimated non-taxable items. The assumptions about future taxable income require significant judgment and are consistent with the plans and estimates we use to manage our businesses. A valuation allowance is established when it is more likely than not that some portion of the deferred tax asset will not be realized. A liability for uncertain tax positions is recorded when it is more likely than not that a tax position will not be sustained upon examination by taxing authorities. The effect of a change in tax rates is recognized in the period of enactment. If we were to be levied interest and penalties by the Internal Revenue Service (“IRS”), the interest would be recognized as “Interest expense” and the penalties would be recognized as either “Other insurance expenses” or "Corporate expenses" on the Consolidated Statements of Income depending on the nature of what caused the occurrence of such an item.

For information regarding the impact of the the recent tax reform, refer to Note 13. "Federal Income Taxes" of this Form 10-K.

Leases

We have various operating leases for office space, equipment, and fleet vehicles. Rental expense for such leases is recorded on a straight-line basis over the lease term. If a lease has a fixed and determinable escalation clause, or periods of rent holidays, the difference between rental expense and rent paid is included in "Other liabilities" in the Consolidated Balance Sheets.

In addition, we have various capital leases for computer hardware and software. These leases are accounted for as an acquisition of an asset with a corresponding obligation. Depreciation is calculated using the straight-line method over the shorter of the estimated useful life of the asset or the lease term.

Pension

Our pension and post-retirement life benefit obligations and related costs are calculated using actuarial methods, within the framework of GAAP. Our pension benefit obligation is determined as the actuarial present value of the vested benefits to which the employee is currently entitled, based on the average life expectancy of the employee. Our funding policy provides that payments to our pension trust shall be equal to the minimum funding requirements of the Employee Retirement Income Security Act, plus additional amounts that the Board of Directors of Selective Insurance Company of America (“SICA”) may approve from time to time.

Two key assumptions, the discount rate and the expected return on plan assets, are important elements of expense and/or liability measurement. We evaluate these key assumptions annually unless facts indicate that a more frequent review is required. The discount rate enables us to state expected future cash flows at their present value on the measurement date. The purpose of the discount rate is to determine the interest rates inherent in the price at which pension benefits could be effectively settled. Our discount rate selection is based on high-quality, long-term corporate bonds. To determine the expected long-term rate of return on the plan assets, we consider the current and expected asset allocation, as well as historical and expected returns on each plan asset class. Other assumptions involve demographic factors such as retirement age and mortality.