Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2012

Stock-Based Compensation

Schedule of weighted-average fair values and assumptions used in calculation of fair value of stock options and employee stock purchase plan

	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2012			2011			2012			2011
Expected volatility:
Stock options	46		%	46		%	46		%	47		%
ESPP	44		%	—		%	46		%	—		%
Risk-free interest rate:
Stock options	1.05		%	1.97		%	1.23		%	2.30		%
ESPP	0.07		%	—		%	0.06		%	—		%
Expected life in years:
Stock options	6.83			5.71			6.83			6.20
ESPP	0.50			—			0.50			—
Weighted-average fair value:
Stock options	$	16.25		$	11.65		$	14.17		$	11.18
ESPP	$	7.48		$	—		$	7.32		$	—