Plan of Liquidation - Additional Information (Detail) (USD $)	12 Months Ended	48 Months Ended
	Mar. 31, 2015	Mar. 31, 2015	Mar. 31, 2014	Dec. 15, 2011	Mar. 31, 2011
Class of Warrant or Right [Line Items]
Allowed General Unsecured Claims					$ 29,771,000,000
Disputed General Unsecured Claims	20,000,000	20,000,000			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
Amount of Term Loan Avoidance Action					1,500,000,000
Dividends received	20,600,000
Dividends declared per share for accrued dividend	$ 0.36
Accrued dividends record date	Jun. 10, 2015
Contribution from MLC					52,700,000
Initial Reporting Cash					5,700,000
Aggregate Other Administrative Cash	14,500,000	14,500,000
New GM Securities with an aggregate fair market value	67,500,000	67,500,000	51,600,000
Dividend Cash set aside for projected Trust fees, costs and expenses	1,300,000	1,300,000
New GM Securities set aside for projected income taxes on dividends received on Common Stock fair market value	19,700,000	19,700,000
New GM Securities set aside for potential Taxes on Distribution	297,200,000	297,200,000	536,300,000
Dividend Cash set aside for potential Taxes on Distribution	5,500,000	5,500,000
Capital loss carryovers	187,100,000	187,100,000
Net operating loss carryovers	86,200,000	86,200,000
Residual Wind-Down assets				42,800,000
Residual Wind-Down Assets cash				40,000,000
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	4,000,000	4,000,000
Residual Wind-Down Assets held by the GUC Trust aggregated	28,300,000	28,300,000
Remaining Residual Wind-Down Claims	500,000	500,000
Cash received for funding Indenture Trustee Fiscal and Paying Agent Costs and Reporting Costs				3,400,000
Agents Costs held by the GUC Trust	400,000	400,000
Cash received for indenture trustee and paying agent costs				1,400,000
Cash received for reporting cash				2,000,000
Guc Trust [Member]
Class of Warrant or Right [Line Items]
Reserve for Disputed General Unsecured Claims	50,000,000	50,000,000
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 Securities [Member]
Class of Warrant or Right [Line Items]
Dividend Cash	17,000,000	17,000,000
Sales of New GM Securities aggregated		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	8,300,000	8,300,000
Residual Wind-Down Assets held by the GUC Trust aggregated	28,200,000	28,200,000
Other Assets And Deposits [Member]
Class of Warrant or Right [Line Items]
Residual Wind-Down Assets held by the GUC Trust aggregated	$ 100,000	$ 100,000
New GM Common Stock [Member]
Class of Warrant or Right [Line Items]
Distributable assets number of securities					150,000,000
Number of securities sold to fund costs and expenses		1,043,801