Related Party Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transactions (Textual) [Abstract]
Business Acquisition, Cost of Acquired Entity, Cash Paid		$ (203,996,000)	$ (79,851,000)
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	473,389
Percentage Of Outstanding Preferred Stock Purchased	34.00%
Chief Executive Officer [Member]
Related Party Transactions (Textual) [Abstract]
Percentage of ownership interest of Chief Operating Officer	54.00%
Chief Operating Officer [Member]
Related Party Transactions (Textual) [Abstract]
Percentage of ownership interest of Chief Operating Officer	8.00%
Akin Gump Strauss Hauer Feld [Member]
Related Party Transactions (Textual) [Abstract]
Business acquisition, total cost	551,000	1,600,000	2,300,000
VetSource [Member]
Related Party Transactions (Textual) [Abstract]
Business acquisition, total cost	$ 13,100,000	$ 28,200,000	$ 41,900,000