Impaired Loans (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Impaired Loans And Leases By Type [Line Items]
Guaranteed portion of education loans	$ 13,697	$ 24,641
Period for loans deemed as non-accrual to return to accrual status	90 days	90 days
Guarantee provided by government agencies against outstanding balances of education loans	97.00%	97.00%