Acquisitions (Details 2) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid			$ (203,996,000)	$ (79,851,000)
Revenue	135,114
Net Income	(6,795)
Business Acquisition, Pro Forma Revenue		1,759,471	1,731,228
Business Acquisition, Pro Forma Net Income (Loss)		47,770	108,406
Business Acquisition, Contingent Consideration, at Fair Value	1,306,000	1,306,000	560,000	259,000
Vetstreet [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid			146,420,000
Business Acquisition, Purchase Price Allocation, Tangible Assets			8,565,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets			45,810,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount			96,149,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed			(4,104,000)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			146,420,000
Pet DRx [Member]
Business Acquisition [Line Items]
Business Acquisition Cost Of Acquired Entity Cash Paid For Hold Backs				750,000
Fair value of total consideration transferred				37,952,000
Business Acquisition, Purchase Price Allocation, Tangible Assets				20,031,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets				3,074,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount				41,686,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed				(26,839,000)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net				37,952,000
Business Acquisition Cost Of Acquired Entity Cash Paid To Bondholders				29,532,000
Business Acquisition Cost of Acquired Entity Cash Paid To Shareholders				7,670,000
BrightHeart [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid			23,490,000
Fair value of total consideration transferred			50,019,000
Business Acquisition, Purchase Price Allocation, Tangible Assets			18,921,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets			8,796,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount			39,806,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed			(17,504,000)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			50,019,000
Business Acquisition Cost Of Acquired Entity Cash Paid To Bondholders			26,048,000
Business Acquisition, Contingent Consideration, at Fair Value			481,000
Think Pets Inc [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid	7,468,000	7,468,000
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	10,500,000	10,500,000
Business Acquisition Cost Of Acquired Entity Cash Paid For Hold Backs	1,050,000	1,050,000
Fair value of total consideration transferred	19,018,000	19,018,000
Business Acquisition, Purchase Price Allocation, Tangible Assets	2,093,000	2,093,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets	7,221,000	7,221,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	12,155,000	12,155,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed	(2,451,000)	(2,451,000)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 19,018,000	$ 19,018,000