Share-Based Compensation (Policy)

12 Months Ended

Dec. 31, 2017

Share-Based Compensation [Abstract]

Share-Based Compensation Policy

We provide for various forms of share-based compensation awards to our employees and non-employee directors. Our share-based compensation plans allow for the issuance of a mix of stock options, restricted stock, stock appreciation rights, employee stock purchase rights and other stock unit awards.With the exception of stock options, the fair value of our awards is equal to the closing stock price of IDEXX common stock on the date of grant. We calculate the fair value of our stock option awards using the Black-Scholes-Merton option-pricing model. For stock options, restricted stock units (“RSUs”), and “deferred stock units (DSUs”), share-based compensation expense is recognized net of estimated forfeitures, on a straight-line basis over the requisite service period of the award for stock options.For performance-based restricted stock units (PBRSUs”), s