Disclosure of Compensation Related Costs, Share-based Payments [Text Block] | 10. Stock-Based Compensation Total stock-based compensation expense in the Company’s unaudited Consolidated Statements of Income related to the Company’s long-term incentive award plans was as follows (in thousands) Three Months Ended 2016 2015 Cost of services-compensation $ 1,931 $ 1,341 Selling, general and administrative 2,309 1,904 Total $ 4,240 $ 3,245 Stock Options The Company’s stock option activity for the three months ended March 31, 2016 (in thousands, except for weighted average exercise price and weighted average remaining contractual term) Shares Weighted Weighted Aggregate Outstanding at December 31, 2015 5,030 $ 17.37 Granted 983 13.90 Exercised (10 ) 2.85 Forfeitures (27 ) 18.88 Expired (69 ) 24.63 Outstanding at March 31, 2016 5,907 16.73 5.21 6,503 Expected to vest at March 31, 2016 3,830 15.77 6.21 2,508 Exercisable at March 31, 2016 1,990 $ 18.59 3.23 $ 3,944 For awards subject to service-based vesting conditions, HMS recognizes stock-based compensation expense, net of estimated forfeitures, equal to the grant date fair value of stock options on a straight-line basis over the requisite service period, which is generally the vesting term. For awards subject to both performance and service-based vesting conditions, HMS recognizes stock-based compensation expense using the straight-line recognition method when it is probable that the performance condition will be achieved. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The fair value of each option grant with service-based vesting conditions was estimated using a Black-Scholes option-pricing valuation model. The performance share awards granted in 2016 and 2015 are market condition awards as attainment is based on the performance of the Company’s common stock for the relevant performance period. These awards were valued on the date of grant using a Monte Carlo simulation model. Expected volatilities are calculated based on the historical volatility of the Company’s common stock. Management monitors stock option exercises and employee termination patterns to estimate forfeiture rates within the valuation model. Separate groups of employees that have similar historical exercise behavior are considered separately for valuation purposes. The expected holding period of options represents the period of time that options granted are expected to be outstanding. The expected terms of options granted are based on the Company’s historical experience for similar types of stock option awards. The risk-free interest rate is based on U.S. Treasury Notes. The weighted average grant-date fair value per share of the stock options granted during the three months ended March 31, 2016 and 2015 was $5.45 and $5.89, respectively. HMS estimated the fair value of each stock option grant on the date of grant using a Black-Scholes option-pricing model and the weighted-average assumptions set forth in the following table: Three Months Ended 2016 2015 Expected dividend yield 0% 0% Risk-free interest rate 1.20% 1.44% Expected volatility 43.89% 38.29% Expected life (in years) 4.90 4.88 During the three months ended March 31, 2016 and 2015, HMS issued 0.01 million shares and 0.4 million shares, respectively, of the Company’s common stock upon the exercise of outstanding stock options and received proceeds of $0.03 million and $3.3 million, respectively. For the three months ended March 31, 2016 and 2015, stock-based compensation expense for stock options was $2.0 million and $1.4 million, respectively. Excess tax benefit from the exercise of stock options for the three months ended March 31, 2016 was $0.01 million and for the year ended December 31, 2015 was $1.6 million, respectively. The total intrinsic value of options exercised (the difference in the market price of the Company’s common stock on the exercise date and the price paid by the optionees to exercise the options) for the three months ended March 31, 2016 and 2015 was approximately $0.1 million and $5.4 million, respectively. As of March 31, 2016, there was approximately $17.6 million of total unrecognized compensation cost, adjusted for estimated forfeitures, related to stock options outstanding, which is expected to be recognized over a weighted average period of 1.47 years. Restricted Stock Units HMS non-employee members of the Company’s Board of Directors and certain employees have received restricted stock units under the Fourth Amended and Restated 2006 Stock Plan (the “2006 Stock Plan”). The fair value of restricted stock units is estimated based on the closing sale price of the Company’s common stock on the NASDAQ Global Select Market on the date of issuance. The total number of restricted stock units expected to vest is adjusted by estimated forfeiture rates. For the three months ended March 31, 2016, HMS granted 562,645 restricted stock units with an aggregate fair market value of $7.8 million. For the three months ended March 31, 2016 and 2015, stock-based compensation expense for restricted stock units was $2.2 million and $1.8 million, respectively. As of March 31, 2016, 1,348,340 restricted stock units remained unvested and there was approximately $18.7 million of unamortized compensation cost related to these restricted stock units, which is expected to be recognized over the remaining weighted-average vesting period of 1.51 years. A summary of the status of the Company’s restricted stock units and of changes in restricted stock units outstanding under the 2006 Stock Plan for the three months ended March 31, 2016 is as follows (in thousands, except for weighted average grant date fair value per unit) Number of Weighted Average Aggregate Outstanding balance at December 31, 2016 1,154 $ 18.85 Granted 563 13.94 Vesting of restricted stock units, net of shares withheld for taxes (133 ) 19.23 Shares withheld for taxes (73 ) 19.23 Forfeitures (22 ) 18.68 Outstanding balance at March 31, 2016 1,489 $ 16.92 $ 21,366 |