Share-Based Compensation

9 Months Ended

Sep. 30, 2011

Share-Based Compensation [Abstract]

Share-Based Compensation

NOTE 3.  SHARE-BASED COMPENSATION

The fair value of options, restricted stock units, deferred stock units with vesting conditions and employee stock purchase rights awarded during the three and nine months ended September 30, 2011 totaled $0.1 million and $23.6 million, respectively, compared to $0.5 million and $15.8 million for the three and nine months ended September 30, 2010, respectively.

The total unrecognized compensation expense, net of estimated forfeitures, for unvested share-based compensation awards outstanding at September 30, 2011 was $32.4 million, which will be recognized over a weighted average of approximately 1.9 years.

Options

We determine the assumptions used in the valuation of option awards as of the date of grant. Differences in the stock price volatility, expected term or risk-free interest rate may result in distinct valuation assumptions at each grant date. As such, we may use different assumptions for options granted throughout the year. Option awards are granted with an exercise price equal to the closing market price of our common stock at the date of grant. We have never paid any cash dividends on our common stock and we have no present intention to pay a dividend; therefore, we assume that no dividends will be paid over the expected terms of option awards.The weighted averages of the valuation assumptions used to determine the fair value of each option award on the date of grant and the weighted average estimated fair values were as follows:

	For the Nine Months Ended September 30,
	2011			2010
Expected stock price volatility		33	%		31	%
Expected term, in years		4.8			4.9
Risk-free interest rate		2.3	%		2.3	%
Weighted average fair value of options granted	$	24.87		$	16.56