Earnings per share

9 Months Ended

Sep. 30, 2011

10. Earnings per share. Basic earnings per share are computed based upon the weighted average number of common shares outstanding, and diluted earnings per share are computed based upon the weighted average number of common shares outstanding and dilutive common share equivalents (consisting of incentive stock options, non-qualified stock options, restricted stock awards and units and employee stock purchase plan shares) outstanding during the periods using the treasury stock method.

The following is a reconciliation of the shares used to compute basic and diluted earnings per share (in thousands):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2011		2010		2011		2010
Weighted average number of common shares outstanding used to compute basic earnings per share		37,001		36,506		36,866		36,432
Dilutive effect of stock-based awards		768		468		890		588
Number of shares used to compute diluted earnings per share		37,769		36,974		37,756		37,020

The following table outlines the weighted average share equivalents outstanding during each period that were excluded from the computation of diluted earnings per share because the exercise price for these options was greater than the average market price of the Company's shares of common stock during the respective periods that became anti-dilutive when applying the treasury stock method (in thousands):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2011		2010		2011		2010
Anti-dilutive common share equivalents outstanding		1,385		2,432		1,059		1,403