Reserves for Expected Costs of Liquidation and Residual Wind-Down Claims - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Restructuring Cost and Reserve [Line Items]
Expected liquidation period	2017-02
Reserve for Expected Wind-Down Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 1.4	$ 2.4
Reserve for Expected Reporting Costs [Member]
Restructuring Cost and Reserve [Line Items]
Net increase (decrease in) additions to reserves for Expected Costs of Liquidation	$ 0.9	$ (0.6)