Plan of Liquidation - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended	24 Months Ended						24 Months Ended			1 Months Ended
	Mar. 31, 2012	Sep. 30, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 15, 2011	Mar. 31, 2011	Sep. 30, 2014 Cash and Cash Equivalents and Marketable Securities [Member]	Sep. 30, 2014 Other Assets And Deposits [Member]	Mar. 31, 2013 Common Stock [Member]	Mar. 31, 2013 Series A Warrants [Member]	Mar. 31, 2013 Series B Warrants [Member]	Oct. 31, 2014 Subsequent Event [Member]	Mar. 31, 2011 New GM Common Stock [Member]	Mar. 31, 2011 New GM Series A Warrants [Member]	Mar. 31, 2011 New GM Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Allowed General Unsecured Claims						$ 29,771,000,000
Disputed General Unsecured Claims		79,500,000				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
Distributable assets number of securities													150,000,000
Distributable assets number of securities called by warrants														136,363,635	136,363,635
Exercise price per share														$ 10.00	$ 18.33
Dividends received		13,800,000
Dividends declared per share for accrued dividend												$ 0.30
Accrued dividends record date												Dec. 10, 2014
Contribution from MLC						52,700,000
Remaining Administrative Fund aggregated							9,400,000
Remaining Administrative Fund for certain costs and liabilities of the GUC Trust		8,200,000
Remaining Administrative Fund for Wind-Down Costs		1,200,000
Initial Reporting Cash						5,700,000
Proceeds from liquidation of securities to fund Avoidance Action Trust costs	13,700,000
Sales of New GM Securities aggregated			50,200,000
Number of securities sold to fund costs and expenses									902,228	820,205	820,205
Aggregate Other Administrative Cash		9,700,000
New GM Securities with an aggregate fair market value		59,000,000
Dividend Cash set aside for projected Trust fees, costs and expenses		800,000
New GM Securities set aside for projected income taxes on dividends received on common stock fair market value		5,800,000
New GM Securities set aside for potential Taxes on Distribution		247,800,000
Dividend Cash set aside for potential Taxes on Distribution		3,400,000
Capital loss carryovers		185,100,000		185,400,000
Net operating loss carryovers		83,800,000		84,500,000
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		2,000,000
Residual Wind-Down Assets held by the GUC Trust aggregated		30,300,000					30,100,000	200,000
Remaining Residual Wind-Down Claims		1,700,000
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
Cash received for indenture trustee and paying agent costs					1,400,000
Cash received for reporting cash					$ 2,000,000