Segment Reporting (Summary Of Revenue By Product And Service Category) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenue	$ 319,538	$ 315,475	$ 335,649	$ 322,676	$ 307,201	$ 300,954	$ 317,862	$ 292,672	$ 1,293,338	$ 1,218,689	$ 1,103,392
CAG Segment [Member]
Segment Reporting Information [Line Items]
Revenue									1,072,211	999,722	905,655
CAG Segment [Member] | VetLab Instruments And Consumables [Member]
Segment Reporting Information [Line Items]
Revenue									417,051	394,586	354,239
CAG Segment [Member] | Rapid Assay Products [Member]
Segment Reporting Information [Line Items]
Revenue									162,232	154,342	146,538
CAG Segment [Member] | Reference Laboratory Diagnostic And Consulting Services [Member]
Segment Reporting Information [Line Items]
Revenue									407,343	373,919	329,666
CAG Segment [Member] | Practice Management and Digital Imaging Systems and Services [Member]
Segment Reporting Information [Line Items]
Revenue									85,585	76,875	75,212
Water Segment [Member]
Segment Reporting Information [Line Items]
Revenue									84,680	82,125	76,514
LPD Segment [Member]
Segment Reporting Information [Line Items]
Revenue									86,724	94,112	81,177
Other Segment [Member]
Segment Reporting Information [Line Items]
Revenue									$ 49,723	$ 42,730	$ 40,046