Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims - Summary of Activity in Reserves for Residual Wind-Down Claims (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Restructuring And Related Activities [Abstract]
Balance, beginning of period	$ 29,692	$ 31,115	$ 30,855	$ 32,247
Less claims allowed during the period	(255)	(142)	(1,418)	(1,274)
Balance, end of period	$ 29,437	$ 30,973	$ 29,437	$ 30,973