Segment Reporting (Summary Of Revenue By Product And Service Category) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenue	$ 399,685	$ 406,387	$ 413,343	$ 382,477	$ 351,959	$ 383,523	$ 390,122	$ 360,203	$ 1,601,892	$ 1,485,807	$ 1,377,058
CAG Segment [Member]
Segment Reporting Information [Line Items]
Revenue									1,356,287	1,223,064	1,140,292
CAG Segment [Member] | CAG Diagnostics Recurring Revenue [Member]
Segment Reporting Information [Line Items]
Revenue									1,146,527	1,039,252	964,009
CAG Segment [Member] | Vetlab Consumables [Member]
Segment Reporting Information [Line Items]
Revenue									396,526	341,407	312,457
CAG Segment [Member] | VetLab Service and Accessories [Member]
Segment Reporting Information [Line Items]
Revenue									55,176	53,006	50,675
CAG Segment [Member] | Rapid Assay Products [Member]
Segment Reporting Information [Line Items]
Revenue									182,670	165,647	169,547
CAG Segment [Member] | Reference Laboratory Diagnostic And Consulting Services [Member]
Segment Reporting Information [Line Items]
Revenue									512,155	479,192	431,330
CAG Segment [Member] | CAG Diagnostic Capital - Instruments [Member]
Segment Reporting Information [Line Items]
Revenue									99,001	79,993	83,492
CAG Segment [Member] | Customer Information Managment and Diagnostic Imaging Systems [Member]
Segment Reporting Information [Line Items]
Revenue									110,759	103,819	92,791
Water Segment [Member]
Segment Reporting Information [Line Items]
Revenue									96,884	94,725	87,959
LPD Segment [Member]
Segment Reporting Information [Line Items]
Revenue									127,143	141,179	123,688
Other Segment [Member]
Segment Reporting Information [Line Items]
Revenue									$ 21,578	$ 26,839	$ 25,119