Income Tax (Provision) Benefit (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Deferred tax assets:
Reserves for expected costs of liquidation	$ 19,482
Net operating losses	15,571
Gross deferred tax assets	35,053
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities	(55,371)
Gross deferred tax liabilities	(55,371)
Net deferred tax liability	$ 20,318	$ 108,583