Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims and Costs - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation		$ 6,483	$ 5,315	$ 9,521	$ 5,043
Expected liquidation end date	2020-01
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		1,719	1,666	4,730	1,356
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation		$ 4,764	$ 3,649	$ 4,791	$ 3,687