Acquisitions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012 years	Sep. 30, 2010 Centaur Services Limited [Member] years	Sep. 30, 2011 Nelson Laboratories [Member] years	Sep. 30, 2012 Micro Beef Technologies [Member] years
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement		February 8, 2010	March 21, 2011	October 31, 2011
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 44,053	$ 7,000	$ 60,878
Business Acquisition, Cost of Acquired Entity, Cash Paid		42,053		53,400
Business Acquisition, Cost of Acquired Entity, Transaction Costs		1,100		1,104
Business Acquisition Cost Of Acquired Entity Purchase Price Adjustment		1,868		320
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares				94,359
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable				7,158
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation		2,047
Business Acquisition, Note Payable Assumed		$ 2,000
Finite-Lived Intangible Assets, Useful Life, Minimum (in years)	1	1		5
Finite-Lived Intangible Assets, Useful Life, Maximum (in years)	20	20	10	17
Business Acquisition, Description of Acquired Entity		Centaur is a supplier of animal health products to veterinarians in the United Kingdom. Centaur sells products to both the companion animal market and production animal market.	Nelson is a distributor of animal health products to over 1,100 veterinary practices	Micro is a value-added distributor to the production animal market, including the distribution of micro feed ingredients, pharmaceuticals, vaccines, parasiticides, supplies and other animal health products. Micro also is a leading innovator of proprietary, computerized management systems for the production animal market.
Business Acquisition Goodwill Tax Deductible Life			15	15