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, 2017	Mar. 31, 2016	Mar. 31, 2015
Restructuring Cost and Reserve [Line Items]
Balance, beginning of year	$ 19,957	$ 26,629	$ 29,956
Plus net addition to reserves	237
Plus reclassification of accrued liability	417
Less claims allowed during the period	(19,641)	(6,661)	(3,292)
Balance, end of period	966	19,957	26,629
Trust Professionals [Member]
Restructuring Cost and Reserve [Line Items]
Less costs incurred by trust professionals	$ (4)	$ (11)	$ (35)