Summary of Allowance for Doubtful Accounts Receivable (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Receivables [Abstract]
Balance at Beginning of Period	$ 282	$ 124	$ 177
Additions	38	159	42
Write-offs		(1)	(95)
Balance at End of Period	$ 320	$ 282	$ 124