Summary Of Significant Accounting Policies (Narrative) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) customer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 0	$ 0
Research And Development Costs, Capitalized		0	0	$ 0
Advertising costs		1,700,000	2,100,000	1,200,000
Foreign currency transaction losses		1,100,000	$ (1,300,000)	$ (200,000)
Available-for-sale Securities Valuation, Difference Between Fair Value And Amortized Cost		$ 200,000
Sales Revenue, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Number Of Significant Customers | customer		0
Concentration Risk, Percentage		0.00%
Percentage of IDEXX consolidated total		0.00%
Future Customer Utilization [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Estimate, Percent		5.00%
Change in Accounting Estimate, Increase (Decrease) Revenue		$ 400,000
Scenario, Forecast [Member] | Accounting Standards Update 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ 10,000,000
Scenario, Forecast [Member] | Accounting Standards Update 2016-16 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ 8,000,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue Recognition, Multiple Element Arrangements, Delivery Term, Years		6 years
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue Recognition, Multiple Element Arrangements, Delivery Term, Years		1 year