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, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenue	$ 354,073	$ 338,297	$ 352,583	$ 332,106	$ 319,538	$ 315,475	$ 335,649	$ 322,676	$ 1,377,058	$ 1,293,338	$ 1,218,689
CAG Segment [Member]
Segment Reporting Information [Line Items]
Revenue									1,150,169	1,072,211	999,722
CAG Segment [Member] | CAG Diagnostics Recurring Revenue [Member]
Segment Reporting Information [Line Items]
Revenue									974,004	896,449	829,192
CAG Segment [Member] | VetLab Consumables [Member]
Segment Reporting Information [Line Items]
Revenue									311,359	278,818	255,848
CAG Segment [Member] | VetLab Service and Accessories [Member]
Segment Reporting Information [Line Items]
Revenue									51,891	48,056	45,083
CAG Segment [Member] | Rapid Assay Products [Member]
Segment Reporting Information [Line Items]
Revenue									169,547	162,232	154,342
CAG Segment [Member] | Reference Laboratory Diagnostic And Consulting Services [Member]
Segment Reporting Information [Line Items]
Revenue									441,207	407,343	373,919
CAG Segment [Member] | CAG Diagnostic Captail - VetLab Instruments [Member]
Segment Reporting Information [Line Items]
Revenue									83,374	90,177	93,655
CAG Segment [Member] | Customer Information Managment and Digital Imaging Systems [Member]
Segment Reporting Information [Line Items]
Revenue									92,791	85,585	76,875
Water Segment [Member]
Segment Reporting Information [Line Items]
Revenue									87,959	84,680	82,125
LPD Segment [Member]
Segment Reporting Information [Line Items]
Revenue									113,811	111,308	113,589
Other Segment [Member]
Segment Reporting Information [Line Items]
Revenue									$ 25,119	$ 25,139	$ 23,253