Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims - Summary of Activity in Reserves for Expected Costs of Liquidation (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 24,611	$ 31,278
Plus additions to (reductions in) reserves	(272)	2,331
Less liquidation costs incurred:
Ending Balance	21,882	30,118
Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,135)	(2,120)
Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,223)	(1,285)
Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(99)	(86)
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	16,727	21,089
Plus additions to (reductions in) reserves	(310)	1,447
Less liquidation costs incurred:
Ending Balance	15,027	20,344
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(616)	(1,364)
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(756)	(818)
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(18)	(10)
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	6,379	8,602
Plus additions to (reductions in) reserves	38	884
Less liquidation costs incurred:
Ending Balance	5,368	8,206
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(518)	(754)
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(450)	(450)
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(81)	(76)
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	293	364
Less liquidation costs incurred:
Ending Balance	276	347
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(17)	(17)
Reserve for Residual Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,212	1,223
Less liquidation costs incurred:
Ending Balance	1,211	1,221
Reserve for Residual Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	$ (1)	$ (2)