Income Tax (Provision) Benefit (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Deferred tax assets:
Reserves for expected costs of liquidation	$ 18,850
Net operating losses	18,909
Gross deferred tax assets	37,759
Deferred tax liabilities:
Fair value in excess of tax basis of holdings of New GM Securities	(368,774)
Gross deferred tax liabilities	(368,774)
Net deferred tax liability	$ (331,015)	$ (164,845)