Computation of Net Loss per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	1.5	1.6	1.5	1.6
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	0.3	0.4	0.3	0.4
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	1.2	1.2	1.2	1.2