future product returns based on the Company’s historical experience. Future market conditions and product transitions may require the Company to increase customer incentive programs and incur incremental price protection obligations that could result in additional reductions to revenue at the time such programs are offered. Additionally, certain customer incentive programs require management to estimate the number of customers who will actually redeem the incentive. Management’s estimates are based on historical experience and the specific terms and conditions of particular incentive programs. If a greater than estimated proportion of customers redeem such incentives, the Company would be required to record additional reductions to revenue, which would have a negative impact on the Company’s results of operations.

Valuation and Impairment of Marketable Securities

The Company’s investments in available-for-sale securities are reported at fair value. Unrealized gains and losses related to changes in the fair value of investments are included in accumulated other comprehensive income, net of tax, as reported in the Company’s Consolidated Balance Sheets. Changes in the fair value of investments impact the Company’s net income only when such investments are sold or an other-than-temporary impairment is recognized. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. The Company regularly reviews its investment portfolio to determine if any investment is other-than-temporarily impaired due to changes in credit risk or other potential valuation concerns, which would require the Company to record an impairment charge in the period any such determination is made. In making this judgment, the Company evaluates, among other things, the duration and extent to which the fair value of an investment is less than its cost, the financial condition of the issuer and any changes thereto, and the Company’s intent to sell, or whether it is more likely than not it will be required to sell, the investment before recovery of the investment’s amortized cost basis. The Company’s assessment on whether an investment is other-than-temporarily impaired or not, could change in the future due to new developments or changes in assumptions related to any particular investment.

Allowance for Doubtful Accounts

The Company distributes its products through third-party distributors, cellular network carriers, and resellers and directly to certain education, consumer, and enterprise customers. The Company generally does not require collateral from its customers; however, the Company will require collateral in certain instances to limit credit risk. In addition, when possible the Company does attempt to limit credit risk on trade receivables with credit insurance for certain customers in Latin America, Europe, Asia, and Australia, or by requiring third-party financing, loans or leases to support credit exposure. These credit-financing arrangements are directly between the third-party financing company and the end customer. As such, the Company generally does not assume any recourse or credit-risk-sharing