Acquisitions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	3 Months Ended						6 Months Ended
	Mar. 31, 2012	Mar. 31, 2013 Customer Relationships [Member] Maximum [Member]	Mar. 31, 2013 Customer Relationships [Member] Minimum [Member]	Mar. 31, 2013 Noncompete Agreements [Member] Maximum [Member]	Mar. 31, 2013 Noncompete Agreements [Member] Minimum [Member]	Mar. 31, 2013 Technology [Member] Maximum [Member]	Mar. 31, 2013 Technology [Member] Minimum [Member]	Mar. 31, 2012 Micro Beef Technologies [Member]	Mar. 31, 2012 Micro Beef Technologies [Member] Maximum [Member]	Mar. 31, 2012 Micro Beef Technologies [Member] Minimum [Member]	Mar. 31, 2013 Prescription Containers Inc [Member]	Mar. 31, 2013 Prescription Containers Inc [Member] Customer Relationships [Member]
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement								Oct. 31, 2011			Dec. 31, 2012
Business Acquisition, Cost of Acquired Entity, Purchase Price								$ 60,878			$ 17,006
Business Acquisition, Cost of Acquired Entity, Cash Paid								53,400
Business Acquisition Cost Of Acquired Entity Purchase Price Adjustment								320
Finite-Lived Intangible Assets, Useful Life		20 years	9 years	5 years	1 year	11 years	11 years		17 years	5 years		10 years
Business Acquisition, Description of Acquired Entity								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.			PCI Animal Health was a distributor of companion animal health products to veterinary practices, primarily in the Northeastern United States.
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable								7,158
Business Acquisition Goodwill Tax Deductible Life	15										15
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares								94,359
Finite Lived Intangible Assets Purchase Accounting Adjustments												$ (1,190)