Note 8 - Fair Value of Financial Instruments (Detail) - Off-Balance Sheet Instruments (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Off-balance sheet instruments
Commitments to extend credit	$ 5,888,167	$ 5,337,000
Commitments to extend credit	$ 5,888,167	$ 5,337,000

The fair value of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Name:	us-gaap_FairValueDisclosureOffbalanceSheetRisksAmountAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant