Fair Value Measurements (Tables)

9 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Assets and liabilities measured at fair value on a recurring basis

	December 31, 2012
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	422	$	—	$	—	$	422
Marketable Securities:						—
Municipal commercial paper and demand notes		—		59,316		—		59,316
Corporate commercial paper		—		5,398		—		5,398
Holdings of New GM Securities:
New GM Common Stock		839,007		—		—		839,007
New GM Warrants		846,328		—		—		846,328
Total Assets	$	1,685,757	$	64,714	$	—	$	1,750,471
Liabilities:
Liquidating distributions payable	$	67,704	$	—	$	—	$	67,704

	March 31, 2012
(in thousands)	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	38,396	$	—	$	—	$	38,396
Marketable Securities:
Municipal commercial paper and demand notes		—		25,253		—		25,253
Corporate commercial paper		—		59,317		—		59,317
U.S. government agency bonds		—		2,001		—		2,001
Holdings of New GM Securities:
New GM Common Stock		770,389		—		—		770,389
New GM Warrants		759,873		—		—		759,873
Total Assets	$	1,568,658	$	86,571	$	—	$	1,655,229
Liabilities:
Liquidating distributions payable	$	31,720	$	—	$	—	$	31,720