Derivative - Additional Information (Detail) (Fair Value Hedging [Member], Interest Rate Swap-Fixed to Variable [Member], USD $)	Dec. 31, 2014	Sep. 30, 2014
Fair Value Hedging [Member] \| Interest Rate Swap-Fixed to Variable [Member]
Derivative [Line Items]
Derivatives held to manage interest rate risk	$ 0	$ 0

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant