Amounts Reclassified Out of Accumulated Other Comprehensive Income - Additional Information (Detail) - USD ($)	12 Months Ended
Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income Pre-Tax [Member] \| Maximum [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Amounts reclassified out of AOCI pre-tax basis	$ 300,000	$ 100,000

Amount before tax of reclassification adjustments of other comprehensive income (loss).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580

Name:	us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration