Share Based Awards

We have a stock incentive plan for employees and directors and an employee stock purchase plan. Shares to be issued under these plans will be issued either from authorized but unissued shares or from treasury shares.

We incur stock compensation expense for stock options, restricted stock units ("RSU"), performance restricted stock units ("PRSU") and stock purchased under our employee stock purchase plan ("ESPP"). We receive a tax benefit on stock compensation expense, excluding the direct tax benefits from exercise of stock options, which is reported separately on the consolidated statements of cash flows. We also have indirect tax benefits upon exercise of stock options related to research and development tax credits which were recorded as a reduction of income tax expense. The table below summarizes compensation costs and related tax benefits for the years ended December 31, 2012, 2011 and 2010.



	Year ended December 31,
	2012		2011		2010
Stock compensation expense	$	5,563	$	4,016	$	3,471
Tax benefit from stock-based compensation cost	1,922		1,376		1,153
Indirect tax benefit	209		785		438

As of December 31, 2012, we had $6.5 million of unamortized stock compensation cost which we will recognize as an expense over approximately 1.25 years.

Stock Incentive and Stock Option Plans

Our 2011 Stock Incentive Plan ("2011 Plan") replaced our 2003 Stock Option Plan (“2003 Plan”). Our 2011 Plan initially had 650,000 shares available for issuance, plus the remaining available shares for grant from the 2003 Plan. In 2012, our stockholders approved an amendment to the 2011 plan that increased the shares available for issuance by 750,000, bringing the initial shares available for issuance to 1,400,000, plus the remaining 248,700 shares that remained available for grant from the 2003 Plan. In addition, any forfeited, terminated or expired shares that would otherwise return to the 2003 Plan are available under the 2011 Plan. As of December 31, 2012, the 2011 Plan has 1,650,363 shares of common stock reserved for issuance to employees, which includes 250,363 shares that transferred from the 2003 Plan. Shares issued as options or stock appreciation rights ("SARs") are charged against the 2011 Plan's share reserve as one share for one share issued. Shares subject to awards other than options and SARs are charged against the 2011 Plan's share reserve as 2.09 shares for 1 share issued. Options may be granted with exercise prices at no less than fair market value at date of grant. Options granted under the 2011 Plan may be “non-statutory stock options” which expire no more than ten years from date of grant or “incentive stock options” as defined in Section 422 of the Internal Revenue Code of 1986, as amended. Upon exercise of non-statutory stock options, we are generally entitled to a tax deduction on the exercise of the option for an amount equal to the excess over the exercise price of the fair market value of the shares at the date of exercise; we are generally not entitled to any tax deduction on the exercise of an incentive stock option. The 2011 Plan includes conditions whereby unvested options are cancelled if employment is terminated.

Our 2001 Directors’ Stock Option Plan (the “Directors’ Plan”), initially had 750,000 shares reserved for issuance to members of our Board of Directors, expired in November 2011. Although no new grants may be made under the Director's Plan, grants made under the Director's Plan prior to its expiration continue to remain outstanding. Options not vested terminate if the directorship is terminated.

Stock Options

To date, all options granted under the 2011 Plan, 2003 Plan and Directors' Plan have been non-statutory stock options. The majority of the employee option grants become exercisable five years from the grant date or 25% becomes exercisable after one year from the grant date and the balance vests ratably on a monthly basis over 36 months. The options granted to non-employee directors generally vest one to four years from the grant date. The options generally expire 10 years from the grant date.

The fair value of option grants is calculated using the Black-Scholes option valuation model. The expected term for the 2012 and 2011 option grants was based on historical experience, expected future employee behavior and the Staff Accounting Bulletin #107 simplified method. The expected term for the 2010 option grants was based on expected future employee behavior. We refined our assumptions on our 2011 grants. Our revised assumptions are in the table below. We estimate the volatility of our common stock at the date of grant based on the historical volatility of our common stock, based on the average expected exercise term. The table below summarizes the total stock options granted, total valuation and the weighted average assumptions for the years ended December 31, 2012, 2011 and 2010.



	Year ended December 31,
	2012			2011			2010
Number of options granted	228,328			290,000			243,000
Grant date fair value of options granted (in thousands)	$	3,158		$	4,090		$	2,474
Weighted average assumptions for stock option valuation:
Expected term (years)	4.7			5.0			3.4
Expected stock price volatility	33.6		%	34.5		%	40.2		%
Risk-free interest rate	0.7		%	1.7		%	0.8		%
Expected dividend yield	—		%	—		%	—		%
Weighted average grant price per option	$	47.12		$	43.27		$	34.70
Weighted average grant date fair value per option	$	13.83		$	14.10		$	10.18

A summary of our stock option activity as of and for the year ended December 31, 2012 is as follows:



	Shares		Weighted Average Exercise Price Per Share		Weighted Average Contractual Life (Years)	Aggregate Intrinsic Value
Outstanding at December 31, 2011	2,745,428		$	33.28
Granted	228,328		$	47.12
Exercised	(526,040	)	$	28.22
Forfeited or expired	(2,963	)	$	34.12
Outstanding at December 31, 2012	2,444,753		$	35.66	4.7	$	61,778
Exercisable at December 31, 2012	1,670,325		$	34.66	3.5	$	43,873
Vested or expected to vest, December 31, 2012	2,444,753		$	35.66	4.7	$	61,778

The intrinsic value for options exercisable, outstanding and vested or expected to vest at December 31, 2012 is based on our closing stock price of $60.93 at December 31, 2012 and are before applicable taxes.



	Year ended December 31,
	2012		2011		2010
Intrinsic value of options exercised	$	12,211	$	11,451	$	4,422
Cash received from exercise of stock options	$	14,844	$	7,974	$	2,517
Tax benefit from stock option exercises	$	4,567	$	4,288	$	1,680

Stock Awards

In 2012, we began awarding PRSUs to our executive officers and RSUs to our Board of Directors. PRSUs are awarded to our executive officers to receive shares of common stock if the measurement period goal is met. The executive PRSUs are based on a one-year market condition performance period measured against a total shareholder return metric ("TSR"). If the TSR is less than the 33rd percentile of our peer group index, 0% of the award would be earned. If the TSR is equal or greater than the 33rd percentile and less than the 50th percentile of our peer group companies, 50% of the award would be earned. If the TSR is equal or greater than the 50th percentile and less than the 75th percentile of our peer group companies, 100% of the award will be earned. If the TSR is equal or greater than the 75th percentile of our peer group companies, 200% of the award will be earned. The PRSUs vest in equal yearly installments with one-third of the grant becoming vested on each of the three anniversary dates of the award. Our executive officers earned 200% of their 2012 award because the TSR was above the 75th percentile of our peer companies.

The fair value of the PRSUs is calculated using a Monte Carlo simulation embedded in a lattice model. This calculation used a risk-free interest rate of 0.13%, a closing share price of $46.53, assumed no dividends and assumed no forfeitures. The correlation matrix of stock price returns and volatilities were calculated based on one year preceding January 1, 2012.

In 2012, we granted 15,589 PRSUs in 2012 at a fair value of $43.60 per unit. Our executive officers earned 200% of the PRSUs granted, bringing the total PRSUs granted to 31,178 units. We granted 6,132 RSUs to our Board of Directors which vest on the first anniversary of the grant date. The fair value of the RSUs is based on the stock price on the date of the grant, or $53.81 per unit in 2012.

The table below provides a summary of our PRSU and RSU activity as of and for the year ended December 31, 2012. The number of units granted are adjusted to reflect the PRSUs awards at 200% of their original amounts.



	Number of Units	Weighted Average Contractual Life (Years)	Aggregate Intrinsic Value
Non-vested at December 31, 2011	—
Granted	37,310
Vested	—
Forfeited	—
Non-vested and expected to vest at December 31, 2012	37,310	1.0	$	2,273

ESPP

We have an ESPP under which U.S. employees may purchase up to $25,000 annually of common stock at 85% of its fair market value at the beginning or the end of a six-month offering period, whichever is lower. There are 750,000 shares of common stock reserved for issuance under the ESPP, which is subject to an annual increase of the least of 300,000 shares, two percent of the shares outstanding or such a number as determined by the Board. To date, there have been no increases. As of December 31, 2012, there were 320,849 shares available for future issuance. The ESPP is intended to constitute an “employee stock purchase plan” within the meaning of Section 423 of the Internal Revenue Code. As of December 31, 2012, we had less than $0.1 million of unamortized stock compensation expense from the ESPP which will be recognized in the first quarter of 2013.

The fair value of rights to purchase shares under the ESPP is calculated using the Black-Scholes option valuation model. The table below summarizes the number and intrinsic value of ESPP share purchases and the weighted average valuation assumptions for the 2012, 2011 and 2010 purchase periods.



	Year ended December 31,
	2012			2011			2010
ESPP shares purchased by employees	61,004			57,643			53,739
Intrinsic value of ESPP purchases (in thousands)	$	913		$	530		$	278
Weighted average assumptions for ESPP valuation:
Expected term (in years)	0.5			0.5			0.5
Expected stock price volatility	23.6		%	26.0		%	26.5		%
Risk-free interest rate	0.1		%	0.4		%	0.2		%
Expected dividend yield	—		%	—		%	—		%