Goodwill and Other Long-Lived Assets (Details) $ in Thousands		9 Months Ended
		Sep. 30, 2015 USD ($) Hospital	Dec. 31, 2014 USD ($)
Goodwill [Roll Forward]
Goodwill		$ 1,545,918
Accumulated impairment losses		(130,057)	$ (130,057)
Subtotal		1,489,843	1,415,861
Goodwill acquired		93,900
Foreign translation adjustment		(18,228)
Other	[1]	(1,690)
Goodwill		$ 1,619,900
Number of animal hospitals sold | Hospital		3
Animal Hospital [Member]
Goodwill [Roll Forward]
Goodwill		$ 1,305,558
Accumulated impairment losses		0	0
Subtotal		1,375,188	1,305,558
Goodwill acquired		89,473
Foreign translation adjustment		(18,157)
Other	[1]	(1,686)
Goodwill		1,375,188
Laboratory [Member]
Goodwill [Roll Forward]
Goodwill		97,535
Accumulated impairment losses		0	0
Subtotal		101,632	97,535
Goodwill acquired		4,172
Foreign translation adjustment		(71)
Other	[1]	(4)
Goodwill		101,632
All Other [Member]
Goodwill [Roll Forward]
Goodwill		142,825
Accumulated impairment losses		(130,057)	(130,057)
Subtotal		13,023	$ 12,768
Goodwill acquired		255
Foreign translation adjustment		0
Other	[1]	0
Goodwill		$ 143,080

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