Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims and Costs - Summary of Activity in Reserves for Residual Wind-Down Claims and Costs (Detail) - Liquidation Basis of Accounting [Member] - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Balance, beginning of year	$ 169	$ 966	$ 19,957
Plus net addition to reserves		9	237
Plus reclassification of accrued liability		9	417
Less claims allowed during the period		(815)	(19,641)
Less costs incurred by trust professionals			(4)
Balance, end of year	$ 169	$ 169	$ 966