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	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 31,278	$ 36,486	$ 61,513
Plus additions to (reductions in) reserves	7,711	9,375	(7,910)
Less liquidation costs incurred :
Ending Balance	24,611	31,278	36,486
Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(7,927)	(8,739)	(11,020)
Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(5,309)	(5,438)	(5,722)
Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(1,142)	(406)	(375)
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	21,089	22,529	38,043
Plus additions to (reductions in) reserves	5,592	8,962	(3,843)
Less liquidation costs incurred :
Ending Balance	16,727	21,089	22,529
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(5,625)	(6,834)	(7,736)
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(3,438)	(3,537)	(3,888)
Reserve for Expected Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(891)	(31)	(47)
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	8,602	12,235	20,442
Plus additions to (reductions in) reserves	2,119	413	(4,067)
Less liquidation costs incurred :
Ending Balance	6,379	8,602	12,235
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(2,291)	(1,870)	(2,013)
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(1,800)	(1,801)	(1,799)
Reserve for Expected Reporting Costs [Member] | Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred :
Liquidation costs incurred	(251)	(375)	(328)
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	364	464	499
Less liquidation costs incurred :
Ending Balance	293	364	464
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	(71)	(100)	(35)
Reserve for Avoidance Action Defense Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance			898
Reserve for Avoidance Action Defense Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred :
Liquidation costs incurred			(898)
Reserve for Residual Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,223	1,258	1,631
Less liquidation costs incurred :
Ending Balance	1,212	1,223	1,258
Reserve for Residual Wind-Down Costs [Member] | Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred :
Liquidation costs incurred	$ (11)	$ (35)	$ (373)