Fair Value Measurements - Foreclosed Assets Remeasured and Reported at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed Assets Remeasured at Initial Recognition Carrying Value Of Foreclosed Assets Prior To Remeasurement	$ 0	$ 7
Foreclosed Assets Remeasured at Initial Recognition Charge-offs recognized in the allowance for loan losses	0	0
Fair Value of Foreclosed Assets Remeasured at Initial Recognition	0	7
Foreclosed Assets Remeasured Subsequent to initial Recognition Carrying value of foreclosed assets prior to remeasurement	0	1,823
Foreclosed Assets Remeasured Subsequent to Initial Recognition Write-downs included in other non-interest expense	0	(473)
Fair Value of Foreclosed Assets remeasured subsequent to initial recognition	$ 0	$ 1,350