Holdings of New GM Securities - Additional Information (Detail) (USD $)	Jun. 30, 2014	Mar. 31, 2014
Distribution Made to Limited Partner [Line Items]
Liquidating distributions payable	$ 48,978,000	$ 42,111,000
Liquidating distributions payable in cash	400,000
New GM Securities reserved and set aside for projected GUC Trust fees, costs and expenses	64,300,000
New GM Securities set aside for potential Taxes on Distribution	552,000,000
Projected Dividend Taxes	5,400,000
New GM Common Stock [Member]
Distribution Made to Limited Partner [Line Items]
Number of warrants or shares pending distribution	627,650
Number of securities set aside from distribution	7,966,477
New GM Series A Warrants [Member]
Distribution Made to Limited Partner [Line Items]
Number of warrants or shares pending distribution	570,485
Number of warrants set aside from distribution	7,242,226
New GM Series B Warrants [Member]
Distribution Made to Limited Partner [Line Items]
Number of warrants or shares pending distribution	570,485
Number of warrants set aside from distribution	7,242,226
New GM Securities [Member]
Distribution Made to Limited Partner [Line Items]
Liquidating distributions payable	$ 48,600,000