Segment Reporting (Summary of Segment Performance) (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
Segment Reporting Information [Line Items]
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
Income (loss) from operations	115,347	117,350	145,594	113,044	97,808	100,413	122,564	92,243	491,335	413,028	350,239
Interest expense, net									(33,593)	(31,971)	(28,393)
Income before provision for income taxes									457,742	381,057	321,846
Provision for income taxes									80,695	117,788	99,792
Net income									377,047	263,269	222,054
Less: Net income attributable to noncontrolling interest									16	125	9
Net income attributable to IDEXX Laboratories, Inc. stockholders	$ 85,638	$ 93,251	$ 108,691	$ 89,451	$ 38,257	$ 70,511	$ 85,357	$ 69,019	377,031	263,144	222,045
Depreciation and amortization									83,178	83,140	78,218
Expenditures for long-lived assets									115,751	74,384	64,787
CAG
Segment Reporting Information [Line Items]
Revenue									1,935,428	1,703,377	1,522,689
Water
Segment Reporting Information [Line Items]
Revenue									125,198	114,395	103,579
LPD
Segment Reporting Information [Line Items]
Revenue									130,581	128,481	126,491
Other
Segment Reporting Information [Line Items]
Revenue									22,035	22,805	22,664
Operating Segments | CAG
Segment Reporting Information [Line Items]
Revenue									1,935,428	1,703,377	1,522,689
Income (loss) from operations									429,483	363,557	301,342
Depreciation and amortization									72,789	71,835	64,878
Expenditures for long-lived assets									103,300	64,759	56,329
Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue									125,198	114,395	103,579
Income (loss) from operations									56,607	50,616	45,702
Depreciation and amortization									2,592	2,856	3,098
Expenditures for long-lived assets									3,172	2,573	2,102
Operating Segments | LPD
Segment Reporting Information [Line Items]
Revenue									130,581	128,481	126,491
Income (loss) from operations									19,412	16,464	18,914
Depreciation and amortization									4,094	5,052	5,543
Expenditures for long-lived assets									4,787	3,021	4,824
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenue									22,035	22,805	22,664
Income (loss) from operations									3,729	4,837	884
Depreciation and amortization									3,703	3,397	4,699
Expenditures for long-lived assets									4,492	4,031	1,532
Unallocated Amounts
Segment Reporting Information [Line Items]
Income (loss) from operations									$ (17,896)	$ (22,446)	$ (16,603)