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	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Plus additions to (reductions in) reserves	$ 3,000	$ 578	$ 7,600	$ (3,500)
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Plus additions to (reductions in) reserves	200	68	(300)	(4,100)
Liquidation Basis of Accounting [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	33,347	43,107	36,486	61,513
Plus additions to (reductions in) reserves	3,200	646	7,335	(7,563)
Less liquidation costs incurred:
Ending Balance	32,632	39,363	32,632	39,363
Liquidation Basis of Accounting [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(2,432)	(2,824)	(6,758)	(9,915)
Liquidation Basis of Accounting [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,368)	(1,446)	(4,156)	(4,356)
Liquidation Basis of Accounting [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(115)	(120)	(275)	(316)
Liquidation Basis of Accounting [Member] | Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	22,042	26,468	22,529	38,043
Plus additions to (reductions in) reserves	2,952	578	7,629	(3,485)
Less liquidation costs incurred:
Ending Balance	22,086	24,509	22,086	24,509
Liquidation Basis of Accounting [Member] | Reserve for Expected Wind-Down Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,997)	(1,551)	(5,324)	(7,033)
Liquidation Basis of Accounting [Member] | Reserve for Expected Wind-Down Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(899)	(973)	(2,728)	(2,977)
Liquidation Basis of Accounting [Member] | Reserve for Expected Wind-Down Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(12)	(13)	(20)	(39)
Liquidation Basis of Accounting [Member] | Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	9,663	14,272	12,235	20,442
Plus additions to (reductions in) reserves	248	68	(294)	(4,078)
Less liquidation costs incurred:
Ending Balance	8,926	13,108	8,926	13,108
Liquidation Basis of Accounting [Member] | Reserve for Expected Reporting Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(431)	(675)	(1,406)	(1,628)
Liquidation Basis of Accounting [Member] | Reserve for Expected Reporting Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(451)	(450)	(1,354)	(1,351)
Liquidation Basis of Accounting [Member] | Reserve for Expected Reporting Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(103)	(107)	(255)	(277)
Liquidation Basis of Accounting [Member] | Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance					408	464	494	499
Less liquidation costs incurred:
Ending Balance	390	471	390	471	408	464	494	499
Liquidation Basis of Accounting [Member] | Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(18)	(23)	(74)	(28)
Liquidation Basis of Accounting [Member] | Reserve for Avoidance Action Defense Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance							588	898
Less liquidation costs incurred:
Ending Balance							588	898
Liquidation Basis of Accounting [Member] | Reserve for Avoidance Action Defense Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred		(588)		(898)
Liquidation Basis of Accounting [Member] | Reserve for Residual Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance					1,234	1,258	1,285	1,631
Less liquidation costs incurred:
Ending Balance	1,230	1,275	1,230	1,275	1,234	1,258	1,285	1,631
Liquidation Basis of Accounting [Member] | Reserve for Residual Wind-Down Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	$ (4)	$ (10)	$ (28)	$ (356)