Business Segment Information - Segment Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 40,466,332	$ 38,169,265
Intersegment eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	(16,317)	(13,514)
Pharmaceutical Distribution Services \| Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	38,937,698	36,798,289
Other \| Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 1,544,951	$ 1,384,490

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration