Contingencies and Loan Commitments - Additional Information (Detail)	Mar. 31, 2013
Commitments Disclosure [Line Items]
Loan commitments fixed and adjusting rate, minimum	4.50%
Loan commitments fixed and adjusting rate, maximum	6.50%

The highest interest rate charged on contract receivables maturing after one year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 910

-SubTopic 310

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6471494&loc=d3e49354-109356

Name:	us-gaap_ContractReceivableDueAfterOneYearHighestInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant