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		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended								3 Months Ended		6 Months Ended								3 Months Ended		6 Months Ended								3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Trust Professionals [Member]	Sep. 30, 2012 Trust Professionals [Member]	Sep. 30, 2013 Trust Professionals [Member]	Sep. 30, 2012 Trust Professionals [Member]	Sep. 30, 2013 Trust Governance [Member]	Sep. 30, 2012 Trust Governance [Member]	Sep. 30, 2013 Trust Governance [Member]	Sep. 30, 2012 Trust Governance [Member]	Sep. 30, 2013 Other Administrative Expenses [Member]	Sep. 30, 2012 Other Administrative Expenses [Member]	Sep. 30, 2013 Other Administrative Expenses [Member]	Sep. 30, 2012 Other Administrative Expenses [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2013 Reserve for Expected Wind-Down Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2012 Reserve for Expected Wind-Down Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2013 Reserve for Expected Reporting Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2012 Reserve for Expected Reporting Costs [Member] Other Administrative Expenses [Member]	Sep. 30, 2013 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Jun. 30, 2013 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Mar. 31, 2013 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Sep. 30, 2012 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Jun. 30, 2012 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Mar. 31, 2012 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member]	Sep. 30, 2013 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] Trust Governance [Member]	Sep. 30, 2012 Reserve for Indenture Trustee/Fiscal and Paying Agent Costs [Member] Trust Governance [Member]	Sep. 30, 2013 Reserve for Avoidance Action Defense Costs [Member]	Jun. 30, 2013 Reserve for Avoidance Action Defense Costs [Member]	Mar. 31, 2013 Reserve for Avoidance Action Defense Costs [Member]	Sep. 30, 2012 Reserve for Avoidance Action Defense Costs [Member]	Jun. 30, 2012 Reserve for Avoidance Action Defense Costs [Member]	Mar. 31, 2012 Reserve for Avoidance Action Defense Costs [Member]	Sep. 30, 2013 Reserve for Avoidance Action Defense Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Avoidance Action Defense Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Avoidance Action Defense Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Avoidance Action Defense Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Residual Wind-Down Costs [Member]	Jun. 30, 2013 Reserve for Residual Wind-Down Costs [Member]	Mar. 31, 2013 Reserve for Residual Wind-Down Costs [Member]	Sep. 30, 2012 Reserve for Residual Wind-Down Costs [Member]	Jun. 30, 2012 Reserve for Residual Wind-Down Costs [Member]	Mar. 31, 2012 Reserve for Residual Wind-Down Costs [Member]	Sep. 30, 2013 Reserve for Residual Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Residual Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2013 Reserve for Residual Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Residual Wind-Down Costs [Member] Trust Professionals [Member]	Sep. 30, 2012 Reserve for Residual Wind-Down Costs [Member] Other Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 53,601	$ 66,304	$ 61,513	$ 76,111													$ 33,594	$ 45,934	$ 38,043	$ 56,815													$ 17,362	$ 15,239	$ 20,442	$ 13,320													$ 494	$ 491	$ 499	$ 572	$ 651	$ 647					$ 588	$ 760	$ 898	$ 1,095	$ 1,240	$ 1,280					$ 1,285	$ 1,394	$ 1,631	$ 2,138	$ 3,240	$ 4,049
Plus additions to (less reductions in) reserves	(6,531)	4,678	(8,209)	5,398													(4,204)	4,265	(4,063)	1,024													(2,327)	413	(4,146)	4,374
Less liquidation costs incurred (net of reversals):
Liquidation costs incurred					(2,427)	(7,612)	(7,091)	(16,481)	(1,480)	(1,621)	(2,910)	(3,213)	(56)	(86)	(196)	(152)					(1,878)	(5,848)	(5,482)	(12,339)	(1,031)	(1,077)	(2,004)	(2,206)	(13)	(13)	(26)	(33)					(268)	(517)	(953)	(2,056)	(452)	(465)	(901)	(932)	(43)	(73)	(170)	(109)							3	(79)	(5)	(75)							(172)	(145)	(310)	(185)							(109)	(1,102)	(346)	(1,901)	(10)
Ending Balance	$ 43,107	$ 61,663	$ 43,107	$ 61,663													$ 26,468	$ 43,261	$ 26,468	$ 43,261													$ 14,272	$ 14,597	$ 14,272	$ 14,597													$ 494	$ 491	$ 499	$ 572	$ 651	$ 647					$ 588	$ 760	$ 898	$ 1,095	$ 1,240	$ 1,280					$ 1,285	$ 1,394	$ 1,631	$ 2,138	$ 3,240	$ 4,049