Stock-Based Compensation | Note 6. Stock-Based Compensation Stock Option The Company granted options to purchase 77,000 and 432,667 shares of common stock to employees during the three and six months ended June 30, 2015 , respectively, and options to purchase 70,000 and 442,010 shares of common stock to employees during the three and six months ended June 30, 2014, respectively. For the three and six months ended June 30, 2015, the Company issued 109,002 and 266,069 shares of common stock in connection with the exercise of stock options with a weighted-average exercise price of $18.47 and $16.51 per share , respectively. For the three and six months ended June 30, 2014, the Company issued 164,441 and 258,750 shares of common stock in connection with the exercise of stock options with a weighted-average exercise price of $11.51 and $11.16 per share, respectively. Performance-Based Vesting Stock Options During the six months ended June 30, 2015, the Company granted performance-based vesting stock options to purchase 148,100 shares of common stock (“PV stock options”). There were no PV stock options granted during the three months ended June 30, 2015 or the three and six months ended June 30, 2014. The number of shares potentially issuable under PV stock options is subject to the attainment of pre-established, objective performance goals over a specified period. In addition, the awards also have a service vesting criteria following the achievement of performance criteria through February 2019. The Company recognizes the fair value of these awards to the extent the achievement of the related performance criteria is estimated to be probable. If a performance criteri on is subsequently determined to not be probable of achievement, any related expense is reversed in the period such determination is made. Conversely, if a performance criteri on is not currently expected to be achieved but is later determined to be probable of achievement, a “catch-up” entry is recorded in the period such determination is made for the expense that would have been recognized had the performance criteri on been probable of achievement since the grant of the award. As of June 30, 2015 , the achievement of the performance criteria wa s not estimated to be probable and therefore the $119,000 of stock-based compensation expense recognized during the three months ended March 31, 2015 related to the PV stock options was reversed during the three months ended June 30, 2015. Changes in the Company’s assessment of the probability of achievement of performance criteria could result in expense being accrued or reversed in future periods. Restricted Stock Units During the three and six months ended June 30, 2015, the Company awarded 24,890 and 384,506 RSUs with a grant-date fair value of $730,000 and $11.9 million, or $29.31 and $31.02 per share , respectively. During the three and six months ended June 30, 2014, the Company awarded 13,934 and 345,187 RSUs with a grant-date fair value of $370,226 and $10.1 million , or $26.57 and $29.16 per share, respectively. Each RSU entitles the recipient to receive one share of the Company’s common stock upon vesting. RSUs awarded to employees generally vest as to one -third of the total number of shares awarded annually over a three -year period. During the three and six months ended June 30, 2015, the Company issued 8,379 and 165,217 shares of common stock in connection with the vesting of RSUs with a weighted-average grant date fair value of $31.35 and $29.68 per share, respectively. During the three and six months ended June 30, 2014, the Company issued 8,141 and 172,673 shares of common stock in connection with the vesting of RSUs with a weighted-average grant date fair value of $31.95 and $28.17 per share, respectively. Performance-Based Vesting Restricted Stock Units During the six months ended June 3 0 , 2015, the Company awarded 22,980 performance-based restricted stock units (“PVRSUs”) with a grant-date fair value of $715,000 , or $31.12 per share. The amount potentially available under a PVRSU is subject to the attainment of pre-established, objective performance goals over a specified period. In addition, the awards have a service vesting criteria following the achievement of performance criteria through February 2018. During the six months ended June 3 0 , 2014, the Company awarded 44,630 PVRSUs with a grant-date fair value of $1.2 million or $27.21 per share. In addition, these awards have a service vesting criteria following the achievement of performance criteria through February 2016. During the six months ended June , 3 0 , 2015, the Company issued 4,227 shares of common stock in connection with the vesting of PVRSUs with a weighted-average grant date fair value of $27.21 per share. As of June 3 0 , 2015, there were 29,133 PVRSUs outstanding with a grant date fair value of $883,000 . The Company recognizes the fair value of these awards to the extent the achievement of the related performance criteria is estimated to be probable. If a performance criteri on is subsequently determined to not be probable of achievement, any related expense is reversed in the period such determination is made. Conversely, if a performance criteri on is not currently expected to be achieved but is later determined to be probable of achievement, a “catch-up” entry is recorded in the period such determination is made for the expense that would have been recognized had the performance criteri on been probable of achievement since the grant of the award. As of June 3 0 , 2015, the achievement of the performance criteria wa s not estimated to be probable , and therefore the $108,000 of stock-based compensation expense recognized during the three months ended March 31, 2015 related to the PVRSUs was reversed during the three months ended June 3 0 , 2015. Changes in the Company’s assessment of the probability of achievement of performance criteria could result in expense being accru ed or reversed in future periods. Restricted Stock in Lieu of Directors’ Fees Outside members of the Company’s Board of Directors may elect to receive fully-vested restricted stock in lieu of cash compensation for services as a director. During the three and six months ended June 30, 2015, the Company issued 1,640 and 3,200 shares of restricted stock to outside directors, with a grant date fair value of $50,000 and $100,000 , and a weighted-average grant date fair value of $30.43 and $31.18 per share , respectively . During the three and six months ended June 3 0 , 2014, the Company issued 2,256 and 3,961 shares of restricted stock to outside directors, with a grant date fair value of $60,000 and $110,000 , and a weighted-average grant date fair value of $26.57 and $27.73 per share , respectively . Employee Stock Purchase Plan During the three and six months ended June 3 0 , 2015 , 108,674 shares of common stock were issued under the Company’s E mployee S tock P urchase P lan (“ESPP”). A total of 1,250,000 shares of common stock have been reserved for issuance under the ESPP, of which 651,064 shares were available for issuance as of June 3 0 , 2015. As of June 3 0 , 2015, there was $554,000 of unrecognized compensation expense related to the ESPP, which is expected to be recognized over a period of five months. Employee Stock-Based Compensation Expense The Company recognized employee stock-based compensation expense of $4.0 million and $8.1 m illion for the three and six months ended June 3 0 , 2015 , respectively, and $4.3 million and $8.6 million for the three and six months ended June 30, 2014, respectively. Employee stock-based compensation expense includes expense related to stock option grants, RSU awards, and stock purchased under the ESPP. Stock-based compensation expense is calculated based on options and RSUs ultimately expected to vest and has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates . Valuation Assumptions The Company values its stock option grants using the Black-Scholes option valuation model. Option valuation models require the input of highly subjective assumptions that can vary over time. The Company’s assumptions regarding expected volatility are based on the historical volatility of the Company’s common stock. The expected life of options granted is estimated based on historical option exercise data and assumptions related to unsettled options. The risk-free interest rate is estimated using published rates for U.S. Treasury securities with a remaining term approximating the expected life of the options granted. The Company uses a dividend yield of zero as it has never paid cash dividends and does not anticipate paying cash dividends in the foreseeable future. |