involves a greater degree of risk and typically involves higher principal amounts than other types of loans. Payments on agricultural loans are typically dependent on the profitable operation or management of the related farm property. The success of the farm may be affected by many factors outside the control of the borrower, including adverse weather conditions that prevent the planting of a crop or limit crop yields (such as hail, drought and floods), declines in market prices for agricultural products (both domestically and internationally) and the impact of government regulations (including changes in price supports, subsidiaries and environmental regulations). In addition, many farms are dependent on a limited number of key individuals whose injury or death may significantly affect the successful operation of the farm. If the cash flow from a farming operation is diminished, the borrower’s ability to repay the loan may be impaired.

At December 31, 2017, our commercial business loans (consisting of commercial and industrial loans, owner-occupied commercial real estate loans and non­owner occupied commercial real estate loans) totaled \$2.25 billion, or approximately 79.1% of our total loan portfolio. Approximately \$9.1 million, or 0.4%, of our total commercial business loans were nonperforming at December 31, 2017. The majority of the nonperforming commercial business loans were owner-occupied commercial real estate loans.

Our non­owner occupied commercial real estate loans, which include five or more family residential real estate loans, involve higher principal amounts than other loans and repayment of these loans may be dependent on factors outside our control or the control of our borrowers. We originate commercial and five or more family residential real estate loans for individuals and businesses for various purposes, which are secured by commercial properties. These loans typically involve higher principal amounts than other types of loans, and repayment is dependent upon income generated, or expected to be generated, by the property securing the loan in amounts sufficient to cover operating expenses and debt service, which may be adversely affected by changes in the economy or local market conditions. For example, if the cash flow from the borrower’s project is reduced as a result of leases not being obtained or renewed, the borrower’s ability to repay the loan may be impaired.

Commercial and five or more family residential real estate loans also expose us to greater credit risk than loans secured by one­to­four family residential real estate because the collateral securing these loans typically cannot be sold as easily as one­to­four family residential real estate. In addition, many of our commercial and five or more family residential real estate loans are not fully amortizing and contain large balloon payments upon maturity. Such balloon payments may require the borrower to either sell or refinance the underlying property in order to make the payment, which may increase the risk of default or non­payment. If we foreclose on a commercial and five or more family residential real estate loan, our holding period for the collateral typically is longer than for one­to­four family residential loans because there are fewer potential purchasers of the collateral. Additionally, commercial and five or more family residential real estate loans generally have relatively large balances to single borrowers or related groups of borrowers. Accordingly, if we make any errors in judgment regarding the collectability of our commercial and five or more family residential real estate loans, any resulting charge­offs may be larger on a per loan basis than those incurred with our residential or consumer loan portfolios.

As of December 31, 2017, our non­owner occupied commercial real estate loans totaled \$986.6 million, or 34.6% of our total loan portfolio. Approximately \$1.9 million, or 0.2%, of our non­owner occupied commercial real estate loans were nonperforming at December 31, 2017.

Our real estate construction and land development loans are based upon estimates of costs and the related value associated with the completed project. These estimates may be inaccurate. Construction lending can involve a higher level of risk than other types of lending because funds are advanced partially based upon the value of the project, which is uncertain prior to the project’s completion. Changes in demand for new housing and higher than anticipated building costs may cause actual results to vary significantly from those estimated. Because of the uncertainties inherent in estimating construction costs as well as the market value of a completed project and the effects of governmental regulation of real property, our estimates with regards to the total funds required to complete a project and the related loan­to­value ratio may vary from actual results. If the estimate of value upon completion proves to be inaccurate, we may be confronted at, or prior to, the maturity of the loan with a project the value of which is insufficient to assure full repayment. In addition, speculative construction loans to a builder are often associated with homes that are not pre­sold, and thus pose a greater potential risk to us than construction loans to individuals on their personal residences. Loans on land under development or held for future construction also pose additional risk because of the lack of income being produced by the property and the potential illiquid nature of the collateral. These risks can be significantly impacted by supply and demand. As a result, this type of lending often involves the disbursement of substantial funds with repayment dependent, in part, on the success of the ultimate project and the ability of the borrower to sell or lease the property or refinance the indebtedness, rather than the ability of the borrower or guarantor to independently repay principal and interest. If our estimate of the value of a project at completion proves to be overstated, we may have inadequate security for repayment of the loan and may incur a loss.