Revenue Recognition (Disaggregation of Revenue by Major Product and Service Categories) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Total revenue	$ 549,386	$ 545,448	$ 580,752	$ 537,656	$ 506,121	$ 491,976	$ 508,940	$ 462,021	$ 2,213,242	$ 1,969,058	$ 1,775,423
CAG segment revenue
Disaggregation of Revenue [Line Items]
Total revenue									1,935,428	1,703,377	1,522,689
CAG segment revenue | CAG Diagnostics recurring revenue
Disaggregation of Revenue [Line Items]
Total revenue									1,654,530	1,451,701	1,281,262
CAG segment revenue | IDEXX VetLab consumables
Disaggregation of Revenue [Line Items]
Total revenue									617,237	518,774	451,456
CAG segment revenue | Rapid assay products
Disaggregation of Revenue [Line Items]
Total revenue									217,541	205,309	189,122
CAG segment revenue | Reference laboratory diagnostic and consulting services
Disaggregation of Revenue [Line Items]
Total revenue									746,794	660,142	581,067
CAG segment revenue | CAG Diagnostics services and accessories
Disaggregation of Revenue [Line Items]
Total revenue									72,958	67,476	59,617
CAG segment revenue | CAG Diagnostics capital - instruments
Disaggregation of Revenue [Line Items]
Total revenue									134,264	119,963	121,191
CAG segment revenue | Veterinary software, services and diagnostic imaging systems
Disaggregation of Revenue [Line Items]
Total revenue									146,634	131,713	120,236
Water segment revenue
Disaggregation of Revenue [Line Items]
Total revenue									125,198	114,395	103,579
LPD segment revenue
Disaggregation of Revenue [Line Items]
Total revenue									130,581	128,481	126,491
Other segment revenue
Disaggregation of Revenue [Line Items]
Total revenue									$ 22,035	$ 22,805	$ 22,664