Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims and Costs - Summary of Activity in Reserves for Expected Costs of Liquidation (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 59,759,000	$ 41,897,000	$ 37,485,000	$ 38,087,000
Plus net additions to (reductions in) reserves	1,634,000	855,000	29,138,000	9,434,000
Less liquidation costs incurred:
Ending Balance	59,065,000	40,559,000	59,065,000	40,559,000
Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,120,000)	(1,016,000)	(4,068,000)	(3,255,000)
Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(1,080,000)	(1,057,000)	(3,229,000)	(3,445,000)
Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(128,000)	(120,000)	(261,000)	(262,000)
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	41,065,000	26,927,000	23,379,000	25,204,000
Plus net additions to (reductions in) reserves	1,639,000	(479,000)	22,362,000	3,944,000
Less liquidation costs incurred:
Ending Balance	41,488,000	25,305,000	41,488,000	25,305,000
Reserve for Expected Wind-Down Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(567,000)	(488,000)	(2,309,000)	(1,655,000)
Reserve for Expected Wind-Down Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(615,000)	(616,000)	(1,852,000)	(2,082,000)
Reserve for Expected Wind-Down Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(34,000)	(39,000)	(92,000)	(106,000)
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	18,596,000	14,847,000	13,996,000	12,739,000
Plus net additions to (reductions in) reserves	(5,000)	1,334,000	6,776,000	5,490,000
Less liquidation costs incurred:
Ending Balance	17,494,000	15,121,000	17,494,000	15,121,000
Reserve for Expected Reporting Costs [Member] | Trust Professionals [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(553,000)	(528,000)	(1,759,000)	(1,600,000)
Reserve for Expected Reporting Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(450,000)	(451,000)	(1,350,000)	(1,352,000)
Reserve for Expected Reporting Costs [Member] | Other Administrative Expenses [Member]
Less liquidation costs incurred:
Liquidation costs incurred	(94,000)	(81,000)	(169,000)	(156,000)
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	98,000	123,000	110,000	144,000
Less liquidation costs incurred:
Ending Balance	83,000	133,000	83,000	133,000
Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] | Trust Governance [Member]
Less liquidation costs incurred:
Liquidation costs incurred	$ (15,000)	$ 10,000	$ (27,000)	$ (11,000)