Stock-Based Compensation Expense	12 Months Ended
Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Expense	. Stock-Based Compensation Expense The Company recorded stock-based compensation expense of $2,021 and $1,494 for 2021 and 2020, respectively. Stock Options The Company uses the Black-Scholes option-pricing model to estimate the fair value of options. This model requires the input of highly subjective assumptions including the expected volatility, risk-free interest rate and the expected life of options. There were no stock options granted in 2021 and 2020, respectively. The Company estimates the expected volatility of its common stock and expected life of its stock options based on its own historical experience. The expected volatility reflects the actual historical volatility of the price of the Company’s common stock since it began trading publicly in March 2013. The expected life represents the period of time that stock options are expected to be outstanding, based on historical exercise and employee departure behavior. The Company has no history or expectation of paying cash dividends on its common stock. The risk-free interest rate is based on the U.S. Treasury yield for a term consistent with the expected life of the options in effect at the time of grant. The Company recognizes stock-based compensation expense only for those shares expected to vest over the requisite service period of the underlying award. The company determines its estimated forfeiture rated based on an analysis of its actual forfeitures and will continue to evaluate the appropriateness of the forfeiture rate based on recent forfeiture activity and expected future employee turnover, if any. Changes in the estimated forfeiture rate can have a significant effect on reported stock-based compensation expense, as the cumulative effect of adjusting the rate for all expense is recognized in the period the forfeiture estimate is changed. No compensation cost is recorded for stock options that do not vest, and the compensation cost for vested stock options, whether forfeited or not, is not reversed. There were no exercises of stock options in 2021 and 2020. As of December 31, 2021 and 2020, there was $82 and $92, respectively, of unrecognized compensation cost, adjusted for estimated forfeitures, related to options, which is expected to be recognized over a weighted-average period of 0.6 and 1.7 years, respectively. RSUs As of December 31, 2021 and 2020, there was $4,957 and $1,935, respectively, of unrecognized compensation cost, adjusted for estimated forfeitures, related to RSUs, which is expected to be recognized over a weighted-average period of 1.8 years and 2.1 years, respectively. The Company uses the fair market value of the underlying common stock on the dates of grant to determine the fair value of RSUs. Employee Stock Purchase Plan The Company estimates the fair value of purchase rights under the 2013 ESPP using the Black-Scholes valuation model. The fair value of each purchase right under the 2013 ESPP is estimated on the date of grant using the Black-Scholes option valuation model and the straight-line attribution approach with assumptions substantially similar to those used for the valuation of stock option awards, with the exception of the expected life. The expected life is estimated to be six months, which is consistent with the purchase periods under the 2013 ESPP.

Stock-Based Compensation Expense

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

. Stock-Based Compensation Expense

The Company recorded stock-based compensation expense of $2,021 and $1,494 for 2021 and 2020, respectively.

Stock Options

The Company uses the Black-Scholes option-pricing model to estimate the fair value of options. This model requires the input of highly subjective assumptions including the expected volatility, risk-free interest rate and the expected life of options. There were no stock options granted in 2021 and 2020, respectively.

The Company estimates the expected volatility of its common stock and expected life of its stock options based on its own historical experience. The expected volatility reflects the actual historical volatility of the price of the Company’s common stock since it began trading publicly in March 2013. The expected life represents the period of time that stock options are expected to be outstanding, based on historical exercise and employee departure behavior. The Company has no history or expectation of paying cash dividends on its common stock. The risk-free interest rate is based on the U.S. Treasury yield for a term consistent with the expected life of the options in effect at the time of grant.

The Company recognizes stock-based compensation expense only for those shares expected to vest over the requisite service period of the underlying award. The company determines its estimated forfeiture rated based on an analysis of its actual forfeitures and will continue to evaluate the appropriateness of the forfeiture rate based on recent forfeiture activity and expected future employee turnover, if any. Changes in the estimated forfeiture rate can have a significant effect on reported stock-based compensation expense, as the cumulative effect of adjusting the rate for all expense is recognized in the period the forfeiture estimate is changed. No compensation cost is recorded for stock options that do not vest, and the compensation cost for vested stock options, whether forfeited or not, is not reversed.

There were no exercises of stock options in 2021 and 2020.

As of December 31, 2021 and 2020, there was $82 and $92, respectively, of unrecognized compensation cost, adjusted for estimated forfeitures, related to options, which is expected to be recognized over a weighted-average period of 0.6 and 1.7 years, respectively.

RSUs

As of December 31, 2021 and 2020, there was $4,957 and $1,935, respectively, of unrecognized compensation cost, adjusted for estimated forfeitures, related to RSUs, which is expected to be recognized over a weighted-average period of 1.8 years and 2.1 years, respectively. The Company uses the fair market value of the underlying common stock on the dates of grant to determine the fair value of RSUs.

Employee Stock Purchase Plan

The Company estimates the fair value of purchase rights under the 2013 ESPP using the Black-Scholes valuation model. The fair value of each purchase right under the 2013 ESPP is estimated on the date of grant using the Black-Scholes option valuation model and the straight-line attribution approach with assumptions substantially similar to those used for the valuation of stock option awards, with the exception of the expected life. The expected life is estimated to be six months, which is consistent with the purchase periods under the 2013 ESPP.