Income Tax Benefit (Provision) - Summary of Deferred Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Deferred tax assets:
Reserves for expected costs of liquidation	$ 10,066	$ 13,414
Net operating and capital loss carryovers	108,227	106,867
Gross deferred tax assets	118,293us-gaap_DeferredTaxAssetsGross	120,281us-gaap_DeferredTaxAssetsGross
Less: Valuation allowance	(35,966)	(71,197)
Deferred tax asset, net of valuation allowance	82,327us-gaap_DeferredTaxAssetsNet	49,084us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities	(71,560)	(49,084)
Accrued dividends and interest	(10,767)
Gross deferred tax liabilities	(82,327)us-gaap_DeferredIncomeTaxLiabilities	(49,084)us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax liability	$ 0us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 0us-gaap_DeferredTaxAssetsLiabilitiesNet

Reserves for expected costs of liquidation.

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Deferred tax liabilities accrued dividends and interest.

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Deferred tax liability fair value in excess of tax basis of securities.

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Amount of deferred tax liability attributable to taxable temporary differences.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Deferred Tax Liability

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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