Income Tax Provision - Summary of Deferred Taxes (Detail) $ in Thousands	Jun. 30, 2015 USD ($)
Deferred tax assets:
Reserves for expected costs of liquidation	$ 11,362
Net operating and capital loss carryovers	108,377
Gross deferred tax assets	119,739
Less: Valuation allowance	(98,015)
Deferred tax asset, net of valuation allowance	21,724
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities	(21,253)
Accrued interest	(471)
Gross deferred tax liabilities	(21,724)
Net deferred taxes	$ 0