Goodwill and Other Long-Lived Assets (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2015 USD ($) Hospital	Dec. 31, 2014 USD ($)
Goodwill [Line Items]
Goodwill		$ 1,582,427	$ 1,545,918
Accumulated impairment losses		(130,057)	(130,057)
Subtotal		1,452,370	1,415,861
Goodwill acquired		46,695
Foreign translation adjustment		(7,878)
Other	[1]	$ (2,308)
Number of animal hospitals sold | Hospital		2
Animal Hospital [Member]
Goodwill [Line Items]
Goodwill		$ 1,337,678	1,305,558
Accumulated impairment losses		0	0
Subtotal		1,337,678	1,305,558
Goodwill acquired		42,268
Foreign translation adjustment		(7,844)
Other	[1]	(2,304)
Laboratory [Member]
Goodwill [Line Items]
Goodwill		101,669	97,535
Accumulated impairment losses		0	0
Subtotal		101,669	97,535
Goodwill acquired		4,172
Foreign translation adjustment		(34)
Other	[1]	(4)
All Other [Member]
Goodwill [Line Items]
Goodwill		143,080	142,825
Accumulated impairment losses		(130,057)	(130,057)
Subtotal		13,023	$ 12,768
Goodwill acquired		255
Foreign translation adjustment		0
Other	[1]	$ 0

[1] "Other" primarily includes write-offs related to the sale of two animal hospitals partially offset by measurement period adjustments.