Company Granted Common Shares with Immediate Vesting to Outside Directors and Employees (Detail) (Common Stock Awards, USD $)	12 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Common Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Granted	5,515	14,484	7,234
Weighted Average Grant Date Fair Value	$ 30.99	$ 27.83	$ 33.64

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration