Disclosure of Compensation Related Costs, Share-based Payments [Text Block] | 1 5 . Share Plans The Company adopted an equity incentive plan (Plan) on February 10, 2010 in connection with its initial public offering. The Plan, as amended, allows for granting of up to 9.1 million stock-based awards to executives, directors and employees. Awards available for grant under the Plan include stock options, stock appreciation rights, restricted stock, other stock-based awards, and performance-based compensation awards. Total share-based compensation expense related to the Plan was $8,241, $12,612 and $12,368 for the years ended December 31, 2015, 2014 and 2013, respectively, net of estimated forfeitures, which is recorded in operating expenses in the consolidated statements of comprehensive income. Stock Options On June 21, 2013, the Company paid a special cash dividend of $5.00 per share on its common stock. In connection with this special dividend, and pursuant to the terms of the Company’s Plan, certain adjustments were made to stock options outstanding in order to avoid dilution of the intended benefits which would otherwise result as a consequence of the special dividend. As such, the strike price for all outstanding stock options as of the special dividend date, were adjusted by the $5.00 special dividend amount. There was no change to compensation expense as a result of this adjustment. Stock options issued in 2012 - 2015 vest in equal installments over four years, subject to the grantee’s continued employment or service and expire ten years after the date of grant. Stock options issued in 2011 and 2010 vest in equal installments over five years, subject to the grantee’s continued employment or service and expire ten years after the date of grant. Stock option exercises are net-share settled such that the Company withholds shares with value equivalent to the exercise price of the stock option awards plus the employees’ minimum statutory obligation for the applicable income and other employment taxes. Total shares withheld were 272,296, 235,644 and 323,427 in 2015, 2014 and 2013, respectively, and were based on the value of the stock on the exercise dates as determined based upon an average of the Company’s high and low stock sales price on the exercise dates. Total payments for the employees’ tax obligations to the taxing authorities were $9,768, $10,411 and $8,449 in 2015, 2014 and 2013, respectively, and are reflected as a financing activity within the consolidated statements of cash flows. The net-share settlement has the effect of share repurchases by the Company as they reduce the number of shares that would have otherwise been issued. The grant-date fair value of each option grant is estimated using the Black-Scholes-Merton option pricing model. The fair value is then amortized on a straight-line basis over the requisite service period of the awards, which is generally the vesting period. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs. Expected volatility is calculated based on an analysis of historic and implied volatility measures for a set of peer companies. The average expected life is based on the contractual term of the option using the simplified method. The risk-free interest rate is based on U.S. Treasury zero-coupon issues with a remaining term equal to the expected life assumed at the date of grant. The compensation expense recognized is net of estimated forfeitures. Forfeitures are estimated based on actual share option forfeiture history. The weighted-average assumptions used in the Black-Scholes-Merton option pricing model for 2015, 2014 and 2013 are as follows: 201 5 201 4 201 3 Weighted average grant date fair value $ 19.07 $ 26.35 $ 16.30 Assumptions: Expected stock price volatility 41 % 45 % 47 % Risk free interest rate 1.72 % 1.90 % 1.21 % Expected annual dividend per share $ - $ - $ - Expected life of options (years) 6.25 6.25 6.25 The Company periodically evaluates its forfeiture rates and updates the rates it uses in the determination of its stock-based compensation expense. The impact of the change to the forfeiture rates on non-cash compensation expense was immaterial for the years ended December 31, 2015, 2014 and 2013. A summary of the Company’s stock option activity and related information for the years ended December 31, 2015, 2014 and 2013 is as follows: Number of Options Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value ($ in thousands) Outstanding as of December 31, 2012 3,440,042 $ 8.44 9.5 $ 87,001 Granted 253,857 35.04 Exercised (703,326 ) 6.05 Expired (1,625 ) 20.94 Forfeited (51,647 ) 17.02 Outstanding as of December 31, 2013 2,937,301 5.74 9.5 $ 148,369 Granted 187,189 57.21 Exercised (549,282 ) 3.44 Expired (259 ) 15.94 Forfeited (32,810 ) 12.68 Outstanding as of December 31, 2014 2,542,139 9.94 8.5 $ 96,518 Granted 287,165 45.18 Exercised (604,088 ) 3.79 Expired (6,409 ) 50.11 Forfeited (90,793 ) 37.27 Outstanding as of December 31, 2015 2,128,014 15.15 7.7 $ 40,271 Exercisable as of December 31, 2015 1,574,790 6.08 7.5 $ 39,072 As of December 31, 2015, there was $7,342 of total unrecognized compensation cost, net of expected forfeitures, related to unvested options. The cost is expected to be recognized over the remaining service period, having a weighted-average period of 2.5 years. Total share-based compensation cost related to the stock options for 2015, 2014 and 2013 was $4,198, $8,509 and $9,034, respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income. Restricted Stock Restricted stock vesting is net-share settled such that, upon vesting, the Company withholds shares with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes, and then pays those taxes on behalf of the employee. In effect, the Company repurchases these shares and classifies as treasury stock, and pays the cash to the taxing authorities on behalf of the employees to satisfy the tax withholding requirements. Total shares withheld were 65,763, 34,854 and 163,458 in 2015, 2014 and 2013, respectively, and were based on the value of the stock on the vesting dates as determined based upon an average of the Company’s high and low stock sales price on the vesting dates. Total payments for the employees’ tax obligations to the taxing authorities were $3,233, $1,770 and $6,571 in 2015, 2014 and 2013, respectively, and are reflected as a financing activity within the consolidated statements of cash flows. A summary of the Company's restricted stock activity for the years ended December 31, 2015, 2014 and 2013 is as follows: Shares Weighted-Average Grant-Date Fair Value Non-vested as of December 31, 2012 665,071 $ 17.75 Granted 112,494 37.82 Vested (450,537 ) 14.21 Forfeited (22,622 ) 25.36 Non-vested as of December 31, 2013 304,406 29.68 Granted 115,473 54.35 Vested (105,123 ) 28.31 Forfeited (47,472 ) 42.31 Non-vested as of December 31, 2014 267,284 38.72 Granted 193,117 41.31 Vested (183,362 ) 32.56 Forfeited (33,999 ) 47.77 Non-vested as of December 31, 2015 243,040 44.16 As of December 31, 2015, there was $6,723 of unrecognized compensation cost, net of expected forfeitures, related to non-vested restricted stock awards. That cost is expected to be recognized over the remaining service period, having a weighted-average period of 2.0 years. Total share-based compensation cost related to the restricted stock for 2015, 2014 and 2013 was $4,043, $4,103 and $3,074, respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income. During 2015, 2014 and 2013, 16,260, 8,869 and 7,291 shares, respectively, of fully vested stock were granted to certain members of the Company’s board of directors as a component of their compensation for their service on the board. Total compensation cost for these share grants in 2015, 2014 and 2013 was $615, $509 and $260, respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income. |