Income Tax (Provision) Benefit - Summary of Deferred Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Mar. 31, 2013
Deferred tax assets:
Reserves for expected costs of liquidation	$ 14,807
Net operating losses	107,812
Total deferred tax assets	122,619
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities	(154,802)
Total deferred tax liability	(154,802)
Net deferred tax liability	$ (32,183)	$ (164,845)