Segment Reporting (Summary Of Revenue By Product And Service Category) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 506,121	$ 491,976	$ 508,940	$ 462,021	$ 442,996	$ 448,308	$ 466,569	$ 417,550	$ 1,969,058	$ 1,775,423	$ 1,601,892
Rapid Assay Products [Member]
Segment Reporting Information [Line Items]
Revenue									205,309	189,122	182,670
CAG Segment [Member]
Segment Reporting Information [Line Items]
Revenue									1,703,377	1,522,689	1,356,287
CAG Segment [Member] | CAG Diagnostics Recurring Revenue [Member]
Segment Reporting Information [Line Items]
Revenue									1,451,701	1,281,262	1,147,026
CAG Segment [Member] | IDEXX Vetlab Consumables [Member]
Segment Reporting Information [Line Items]
Revenue									518,774	451,456	396,526
CAG Segment [Member] | Reference Laboratory Diagnostic And Consulting Services [Member]
Segment Reporting Information [Line Items]
Revenue									660,142	581,067	512,155
CAG Segment [Member] | CAG Diagnostics Service And Accessories [Member]
Segment Reporting Information [Line Items]
Revenue									67,476	59,617	55,675
CAG Segment [Member] | CAG Diagnostic Capital - Instruments [Member]
Segment Reporting Information [Line Items]
Revenue									119,963	121,191	98,502
CAG Segment [Member] | Veterinary Software, Services And Diagnostic Imaging Systems [Member]
Segment Reporting Information [Line Items]
Revenue									131,713	120,236	110,759
Water [Member]
Segment Reporting Information [Line Items]
Revenue									114,395	103,579	96,884
LPD Segment [Member]
Segment Reporting Information [Line Items]
Revenue									128,481	126,491	127,143
Other [Member]
Segment Reporting Information [Line Items]
Revenue									$ 22,805	$ 22,664	$ 21,578