Segment Reporting (Summary of Segment Performance) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 721,789			$ 605,303			$ 1,985,717	$ 1,801,462
Income from operations	171,856			139,802			509,429	437,215
Interest expense, net	(7,902)			(7,004)			(24,880)	(23,503)
Income before provision for income taxes	163,954			132,798			484,549	413,712
Provision for income taxes	17,633			23,960			77,376	76,464
Net income	146,321	$ 148,996	$ 111,856	108,838	$ 125,701	$ 102,709	407,173	337,248
Less: Net income attributable to noncontrolling interest	102			1			187	24
Net income attributable to IDEXX Laboratories, Inc. stockholders	146,219			108,837			406,986	337,224
CAG
Segment Reporting Information [Line Items]
Revenue	638,017			533,130			1,756,113	1,589,397
Water
Segment Reporting Information [Line Items]
Revenue	33,272			34,906			95,537	99,980
LPD
Segment Reporting Information [Line Items]
Revenue	36,971			31,370			103,369	95,980
Other
Segment Reporting Information [Line Items]
Revenue	13,529			5,897			30,698	16,105
Operating Segments | CAG
Segment Reporting Information [Line Items]
Revenue	638,017			533,130			1,756,113	1,589,397
Income from operations	139,434			117,691			426,062	370,600
Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue	33,272			34,906			95,537	99,980
Income from operations	15,243			16,930			43,383	47,467
Operating Segments | LPD
Segment Reporting Information [Line Items]
Revenue	36,971			31,370			103,369	95,980
Income from operations	10,505			4,850			28,417	17,707
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenue	13,529			5,897			30,698	16,105
Income from operations	$ 6,674			$ 331			$ 11,567	$ 1,441