Earnings Per Share

3 Months Ended

Mar. 31, 2012

Earnings Per Share [Abstract]

Earnings Per Share

Note 12. Earnings per Share

Basic earnings per share is computed by dividing net income attributable to IDEXX Laboratories, Inc. stockholders by the weighted average number of shares of common stock and vested deferred stock units outstanding during the year. Vested deferred stock units outstanding are included in shares outstanding for basic and diluted earnings per share because the associated shares of our common stock are issuable for no cash consideration, the number of shares of our common stock to be issued is fixed and issuance is not contingent. See Note 4 to the consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2011 for additional information regarding deferred stock units. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and assumed issuance of unvested restricted stock units and unvested deferred stock units using the treasury stock method unless the effect is anti-dilutive.

The following is a reconciliation of shares outstanding for basic and diluted earnings per share for the three months ended March 31, 2012 and 2011 (in thousands):

	For the Three Months Ended March 31,
	2012		2011
Shares outstanding for basic earnings per share:		55,208		57,457
Shares outstanding for diluted earnings per share:
Shares outstanding for basic earnings per share		55,208		57,457
Dilutive effect of share-based payment awards		1,231		1,633
		56,439		59,090

Certain options to acquire shares and restricted stock units have been excluded from the calculation of shares outstanding for diluted earnings per share because they were anti-dilutive. The following table presents information concerning those anti-dilutive options and restricted stock units for the three months ended March 31, 2012 and 2011 (in thousands):

	For the Three Months Ended March 31,
	2012		2011
Weighted average number of shares underlying anti-dilutive options		618		256
Weighted average number of shares underlying anti-dilutive restricted stock units		50		53