Segment Reporting (Summary Of Segment Performance) (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
Income (loss) from operations	97,808	100,413	122,564	92,243	83,825	88,459	104,162	73,793	413,028	350,239	299,912
Interest expense, net									(31,971)	(28,393)	(26,771)
Income before provision for income taxes									381,057	321,846	273,141
Provision for income taxes									117,788	99,792	81,006
Net income									263,269	222,054	192,135
Less: Net income attributable to noncontrolling interest									125	9	57
Net income attributable to IDEXX Laboratories, Inc. stockholders	$ 38,257	$ 70,511	$ 85,357	$ 69,019	$ 52,369	$ 56,455	$ 67,202	$ 46,019	263,144	222,045	192,078
Depreciation and amortization									83,140	78,218	68,956
Expenditures for long-lived assets									74,384	64,787	82,921
CAG Segment [Member]
Segment Reporting Information [Line Items]
Revenue									1,703,377	1,522,689	1,356,287
Income (loss) from operations									363,557	301,342	233,319
Depreciation and amortization									71,835	64,878	60,715
Expenditures for long-lived assets									64,759	56,329	69,371
Water [Member]
Segment Reporting Information [Line Items]
Revenue									114,395	103,579	96,884
Income (loss) from operations									50,616	45,702	44,752
Depreciation and amortization									2,856	3,098	3,188
Expenditures for long-lived assets									2,573	2,102	2,781
LPD Segment [Member]
Segment Reporting Information [Line Items]
Revenue									128,481	126,491	127,143
Income (loss) from operations									16,464	18,914	27,157
Depreciation and amortization									5,052	5,543	4,367
Expenditures for long-lived assets									3,021	4,824	9,110
Other [Member]
Segment Reporting Information [Line Items]
Revenue									22,805	22,664	21,578
Income (loss) from operations									4,837	884	(137)
Depreciation and amortization									3,397	4,699	686
Expenditures for long-lived assets									4,031	1,532	1,659
Unallocated Amounts [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations									$ (22,446)	$ (16,603)	$ (5,179)