Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims and Costs - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Feb. 01, 2019
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 9,511	$ 33,948	$ 12,123
Loss contingency Inestimable loss				$ 13,720
Expected liquidation end date	Apr. 30, 2022
Claim for Reimbursement of Legal Fees	$ 6,700
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Loss contingency Inestimable loss	13,720
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	4,122	25,351	5,325
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 5,389	$ 8,597	$ 6,798