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	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	$ 169	$ 160	$ 169	$ 966
Plus net addition to reserves	0	0	0	8
Less claims allowed during the period	0	0	0	(814)
Balance, end of period	$ 169	$ 160	$ 169	$ 160