Fair Value Measurements - Foreclosed Assets Remeasured and Reported at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Foreclosed Assets Remeasured at Initial Recognition [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of foreclosed assets prior to remeasurement	$ 415	$ 1,386
Charge-offs recognized in the allowance for loan losses	(141)	(315)
Fair value	274	1,071
Foreclosed Assets Remeasured Subsequent to Initial Recognition [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of foreclosed assets prior to remeasurement	3,600	372
Write-downs included in other non-interest expense	(565)	(75)
Fair value	$ 3,035	$ 297