Summary of Significant Accounting Policies (Revenue Recognition) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Summary of Significant Accounting Policies [Abstract]
Gross Billings From Agency Contracts	$ 349,006	$ 332,343	$ 371,024
Commission Revenue	$ 18,851	$ 16,979	$ 20,655

Gross amount billed to customers from the vendor related to agency contracts.

No definition available.

Name:	mwiv_GrossBillingsFromAgencyContracts
Namespace Prefix:	mwiv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration