Plan of Liquidation - Additional Information (Detail) - USD ($)		3 Months Ended	6 Months Ended	38 Months Ended	52 Months Ended
	Dec. 15, 2011	Sep. 30, 2019	Sep. 30, 2019	Jan. 31, 2019	Aug. 05, 2015	Jul. 01, 2019	Mar. 31, 2012	Mar. 31, 2011
Class of Warrant or Right [Line Items]
Allowed General Unsecured Claims								$ 29,771,000,000
Disputed General Unsecured Claims		$ 0	$ 0					8,154,000,000
Total aggregate amount of general unsecured claims, both allowed and disputed inclusive of potential Term Loan Avoidance Action Claims								39,425,000,000
Release of general claim contingency		50,000,000	50,000,000
Amount of Term Loan Avoidance Action								1,500,000,000
Dividends received					$ 24,700,000
Contribution from MLC								52,700,000
Initial Reporting Cash								$ 5,700,000
Appropriated Distributable Cash				$ 48,000,000
Distributable Cash set aside for projected Trust fees, costs and expenses		75,700,000	75,700,000
Residual Wind-Down Assets	$ 42,800,000	200,000	200,000
Cash received to fund Avoidance Action Defense Costs	1,400,000
Residual wind-down assets transferred benefit in prepaid expenses	2,800,000
Avoidance action defense costs in excess of corresponding cash		30,200,000	30,200,000
Funds for Indenture Trustee/Fiscal Paying Agent Costs		100,000	100,000
Cash received for indenture trustee and paying agent costs	1,400,000
Cash received for funding Indenture Trustee Fiscal and Paying Agent Costs and Reporting Costs	3,400,000
Cash received for reporting cash	2,000,000
Distributions payable for new allowed general unsecured claims						$ 68,500,000
Recoveries by the avoidance action trust and corresponding new allowed general unsecured claims						$ 231,000,000
Avoidance ActionTrust [Member]
Class of Warrant or Right [Line Items]
Resolved Term Loan Avoidance Action Claims distributions paid		52,500,000
Cash Transferred to trust	500,000
Amount receivable upon dissolution of the trust			400,000
New GM Securities [Member]
Class of Warrant or Right [Line Items]
Aggregate sales of new GM Securities to fund costs and expenses					61,700,000
Aggregate dividend cash associated with sales of New GM Securities to fund costs					$ 200,000
Cash and Cash Equivalents and Marketable Securities [Member]
Class of Warrant or Right [Line Items]
Remaining Administrative Fund aggregated		1,213,000	1,213,000
Aggregate Other Administrative Cash		31,425,000	31,425,000
Residual Wind-Down Assets	$ 40,000,000	176,000	176,000
Funds for Indenture Trustee/Fiscal Paying Agent Costs		$ 108,000	$ 108,000
New GM Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Distributable assets number of securities called by warrants								136,363,635
Exercise price per share								$ 10.00
Warrants expiration date			Jul. 10, 2016
Number of securities sold to fund costs and expenses					948,887
New GM Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Distributable assets number of securities called by warrants								136,363,635
Exercise price per share								$ 18.33
Warrants expiration date			Jul. 10, 2019
Number of securities sold to fund costs and expenses					948,887
New GM Common Stock [Member]
Class of Warrant or Right [Line Items]
Distributable assets number of securities								150,000,000
Securities authorized for sale							$ 13,700,000
Number of securities sold to fund costs and expenses					1,043,801