Segment Reporting (Summary of Segment Performance) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 605,446	$ 605,303	$ 620,103	$ 576,056	$ 549,386	$ 545,448	$ 580,752	$ 537,656	$ 2,406,908	$ 2,213,242	$ 1,969,058
Income (loss) from operations	115,631	139,802	164,275	133,138	115,347	117,350	145,594	113,044	552,846	491,335	413,028
Interest expense, net									(30,628)	(33,593)	(31,971)
Income before provision for income taxes									522,218	457,742	381,057
Provision for income taxes									94,426	80,695	117,788
Net income									427,792	377,047	263,269
Less: Net income attributable to noncontrolling interest									72	16	125
Net income attributable to IDEXX Laboratories, Inc. stockholders	$ 90,496	$ 108,837	$ 125,706	$ 102,681	$ 85,638	$ 93,251	$ 108,691	$ 89,451	427,720	377,031	263,144
Depreciation and amortization									88,011	83,178	83,140
CAG
Segment Reporting Information [Line Items]
Revenue									2,119,183	1,935,428	1,703,377
Water
Segment Reporting Information [Line Items]
Revenue									132,850	125,198	114,395
LPD
Segment Reporting Information [Line Items]
Revenue									132,635	130,581	128,481
Other
Segment Reporting Information [Line Items]
Revenue									22,240	22,035	22,805
Operating Segments | CAG
Segment Reporting Information [Line Items]
Revenue									2,119,183	1,935,428	1,703,377
Income (loss) from operations									491,602	429,483	363,557
Depreciation and amortization									77,620	72,789	71,835
Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue									132,850	125,198	114,395
Income (loss) from operations									62,435	56,607	50,616
Depreciation and amortization									2,794	2,592	2,856
Operating Segments | LPD
Segment Reporting Information [Line Items]
Revenue									132,635	130,581	128,481
Income (loss) from operations									25,374	19,412	16,464
Depreciation and amortization									4,007	4,094	5,052
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenue									22,240	22,035	22,805
Income (loss) from operations									4,940	3,729	4,837
Depreciation and amortization									3,590	3,703	3,397
Unallocated Amounts
Segment Reporting Information [Line Items]
Income (loss) from operations									$ (31,505)	$ (17,896)	$ (22,446)