Income Tax Benefit - Summary of Deferred Taxes (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015
Deferred tax assets:
Reserves for expected costs of liquidation	$ 9,421	$ 10,066
Net operating and capital loss carryovers	112,442	108,227
Gross deferred tax assets	121,863	118,293
Less: Valuation allowance	(121,486)	(35,966)
Deferred tax asset, net of valuation allowance	377	82,327
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities		(71,560)
Accrued investment income	(377)	(10,767)
Gross deferred tax liabilities	(377)	(82,327)
Net deferred taxes	$ 0	$ 0