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, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 61,513	$ 76,111
Plus Funding for expected costs from MLC			63,012
Plus additions to (less reductions in) reserves	(7,910)	17,488	52,993
Less liquidation costs incurred:
Ending Balance	36,486	61,513	76,111
Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(11,020)	(25,487)	(35,879)
Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(5,722)	(6,205)	(3,584)
Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(375)	(394)	(432)
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	38,043	56,815
Plus Funding for expected costs from MLC			52,734
Plus additions to (less reductions in) reserves	(3,843)	5,195	32,434
Less liquidation costs incurred:
Ending Balance	22,529	38,043	56,815
Reserve for Expected Wind-Down Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(7,736)	(19,712)	(25,320)
Reserve for Expected Wind-Down Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(3,888)	(4,191)	(2,866)
Reserve for Expected Wind-Down Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(47)	(64)	(167)
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	20,442	13,320
Plus additions to (less reductions in) reserves	(4,067)	12,293	20,560
Less liquidation costs incurred:
Ending Balance	12,235	20,442	13,320
Reserve for Expected Reporting Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(2,013)	(2,985)	(6,975)
Reserve for Expected Reporting Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,799)	(1,866)
Reserve for Expected Reporting Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(328)	(320)	(265)
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	499
Plus Funding for expected costs from MLC			1,365
Plus additions to (less reductions in) reserves
Less liquidation costs incurred:
Ending Balance	464		647
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(35)	(148)	(718)
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred
Reserve for Avoidance Action Defense Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	898
Plus Funding for expected costs from MLC			1,358
Plus additions to (less reductions in) reserves
Less liquidation costs incurred:
Ending Balance			1,280
Reserve for Avoidance Action Defense Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(898)	(382)	(78)
Reserve for Avoidance Action Defense Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred
Reserve for Avoidance Action Defense Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred
Reserve for Residual Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,631
Plus Funding for expected costs from MLC			7,555
Plus additions to (less reductions in) reserves
Less liquidation costs incurred:
Ending Balance	1,258		4,049
Reserve for Residual Wind-Down Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(373)	(2,408)	(3,506)
Reserve for Residual Wind-Down Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred
Reserve for Residual Wind-Down Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred		$ (10)