6. Stock Plans

The Company’s Amended and Restated 2006 Omnibus Incentive Plan (the “Plan”) permits the grant of stock options, stock appreciation rights, restricted stock, restricted stock units, performance awards and other share-based awards to its directors, employees and consultants. At December 31, 2015, approximately 4.2 million shares of common stock remained available for issuance pursuant to future grants of awards under the 2006 Plan (with a limit of approximately 0.7 million shares available for awards other than stock options or stock appreciation rights).

Stock option awards are generally granted with an exercise price equal to the market price of the Company’s stock at the date of grant and generally expire ten years after the date of grant. Generally, stock options granted to non-employee directors are exercisable after one year from the date of grant, while options granted to employees are exercisable one to four years from the date of grant. The Company records compensation expense equal to the fair value of each stock option award granted on a straight line basis over the option’s vesting period. The fair value of each option award is estimated on the date of grant using the Black-Scholes-Merton option pricing formula. Expected volatilities are based on the historical volatility of the Company’s stock. The Company uses historical data to estimate expected option exercise and employee termination patterns within the valuation model. The expected term of options granted is derived from the output of the option valuation model and represents the period of time that options granted are expected to be outstanding. The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant.

The Company granted no options during 2015, 2014 or 2013. A summary of stock option activity under the Company’s equity incentive plans as of December 31, 2015 and changes during the year ended December 31, 2015 is presented below:


Stock Options	Number of Shares			Weighted Average Exercise Price
Outstanding at January 1, 2015		282,302		$	30.88
Granted		—			—
Exercised		(75,492	)		34.48
Canceled		(301	)		40.33

Outstanding at December 31, 2015		206,509			29.55

Exercisable at December 31, 2015		157,417			31.15

The weighted average remaining contractual term of options outstanding and exercisable as of December 31, 2015 was 4.0 and 3.3 years, respectively. The aggregate intrinsic value of options outstanding and exercisable as of December 31, 2015 was $4.9 million and $3.5 million, respectively. The total intrinsic value of options exercised during 2015, 2014, and 2013 was $1.8 million, $13.0 million, and $4.3 million, respectively.

The Plan also provides for the award of restricted stock and restricted stock units (“Restricted Stock Awards”). Restricted Stock Awards granted to employees vest one to four years from the date of grant, and Restricted Stock Awards granted to non-employee directors vest after one year from the date of grant, unless the recipient chooses to defer the vesting for a period of time. Depending on the type of award, the fair value of Restricted Stock Awards is determined either based on the market price of the Company’s stock at the date of grant or based on a Monte-Carlo valuation. The Company generally records compensation expense equal to the fair value of each Restricted Stock Award granted over the vesting period. The weighted-average grant-date fair value of Restricted Stock Awards granted during 2015, 2014, and 2013 was $57.21, $41.61, and $43.56, respectively.

A summary of the status of the Company’s Restricted Stock Awards as of December 31, 2015 and changes during the year ended December 31, 2015, is presented below:


Restricted Stock Awards	Shares			Weighted Average Grant-Date Fair Value
Nonvested shares at January 1, 2015		589,863		$	36.61
Granted		202,175			57.21
Vested		(250,924	)		32.90
Canceled		(775	)		50.23

Nonvested shares at December 31, 2015		540,339			43.05

The fair value of all Restricted Stock Awards that vested during 2015, 2014 and 2013 was $14.0 million, $7.0 million and $3.2 million, respectively.

As of December 31, 2015, there was $8.9 million of total unrecognized compensation cost related to stock options and restricted stock units granted under the Company’s equity incentive plans. That cost is expected to be recognized over a weighted-average period of 2.3 years.

The compensation cost that has been charged against pre-tax income for all of the Company’s stock-based compensation plans was $6.2 million, $5.8 million, and $11.6 million for 2015, 2014, and 2013, respectively. The total income tax benefit recognized in the accompanying consolidated statements of operations for all of the Company’s stock-based employee compensation plans was $2.0 million, $1.9 million, and $3.0 million for 2015, 2014, and 2013, respectively.

Cash received from option exercises under all stock-based employee compensation arrangements for 2015, 2014, and 2013 was $1.8 million, $6.9 million, and $5.2 million, respectively. The actual tax benefit realized from exercise, vesting or cancellation of the stock-based employee compensation arrangements during 2015, 2014, and 2013 totaled $3.2 million, $3.2 million, and $1.0 million, respectively, and is reflected as an adjustment to either additional paid-in capital in the accompanying consolidated statements of stockholders’ equity or deferred tax liabilities in the accompanying consolidated balance sheets.