Summary of Significant Accounting Policies - Estimated Useful Lives of Intangibles (Details)	12 Months Ended
	Dec. 31, 2015
Animal Hospital [Member] | Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	5 years
Minimum [Member] | Covenants not-to-compete [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	3 years
Minimum [Member] | Favorable lease asset [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	4 years
Minimum [Member] | Technology [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	4 years
Minimum [Member] | Trademarks [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	2 years
Minimum [Member] | Laboratory [Member] | Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	5 years
Minimum [Member] | Other Segments [Member] | Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	5 years
Maximum [Member] | Covenants not-to-compete [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	25 years
Maximum [Member] | Favorable lease asset [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	27 years
Maximum [Member] | Technology [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	10 years
Maximum [Member] | Trademarks [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	10 years
Maximum [Member] | Laboratory [Member] | Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	25 years
Maximum [Member] | Other Segments [Member] | Non-contractual customer relationships [Member]
Amortization of intangible assets estimated useful lives
Amortization of intangible assets estimated useful lives	7 years