Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims and Costs - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 855	$ 6,148	$ 9,434	$ 15,668
Loss contingency Inestimable loss	0		$ 0
Expected liquidation end date			Apr. 30, 2022
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Loss contingency Inestimable loss	13,700		$ 13,700
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	(479)	6,307	3,944	11,037
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 1,334	$ (159)	$ 5,490	$ 4,631