Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Mar. 31, 2014
Goodwill [Line Items]
Goodwill	$ 1,451,728		$ 1,460,865
Accumulated impairment losses	(120,811)		(120,811)
Subtotal	1,330,917		1,340,054
Goodwill acquired	15,115
Foreign translation adjustment	(4,053)
Other	(1,925)	[1]
Animal Hospital [Member]
Goodwill [Line Items]
Goodwill	1,216,581		1,225,741
Accumulated impairment losses	0		0
Subtotal	1,216,581		1,225,741
Goodwill acquired	15,115
Foreign translation adjustment	(4,030)
Other	(1,925)	[1]
Laboratory [Member]
Goodwill [Line Items]
Goodwill	96,871		96,848
Accumulated impairment losses	0		0
Subtotal	96,871		96,848
Goodwill acquired	0
Foreign translation adjustment	(23)
Other	0	[1]
All Other Segments [Member]
Goodwill [Line Items]
Goodwill	138,276		138,276
Accumulated impairment losses	(120,811)		(120,811)
Subtotal	17,465		17,465
Goodwill acquired	0
Foreign translation adjustment	0
Other	$ 0	[1]

[1] "Other" primarily includes measurement period adjustments and an immaterial write-off related to a sale of an animal hospital.