Revenue Recognition (Disaggregation of Revenue by Major Product and Service Categories) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from Contract with Customer, Including Assessed Tax	$ 537,656	$ 462,021
CAG Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax	470,833	403,227
CAG Segment [Member] | CAG Diagnostics Recurring Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax	406,048	346,680
CAG Segment [Member] | IDEXX Vetlab Consumables [Member]
Revenue from Contract with Customer, Including Assessed Tax	149,513	123,553
CAG Segment [Member] | Rapid Assay Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	52,017	47,895
CAG Segment [Member] | Reference Laboratory Diagnostic And Consulting Services [Member]
Revenue from Contract with Customer, Including Assessed Tax	186,937	159,069
CAG Segment [Member] | CAG Diagnostics Service And Accessories [Member]
Revenue from Contract with Customer, Including Assessed Tax	17,581	16,163
CAG Segment [Member] | CAG Diagnostic Capital - Instruments [Member]
Revenue from Contract with Customer, Including Assessed Tax	30,895	26,183
CAG Segment [Member] | Veterinary Software, Services and Diagnostic Imaging Systems [Member]
Revenue from Contract with Customer, Including Assessed Tax	33,890	30,364
Water Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax	29,143	25,077
LPD Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax	32,240	29,317
Other Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 5,440	$ 4,400