Revenue Recognition - Schedule of Deferred Revenues Balance as of Transition Date and Significant Activity Affecting Deferred Revenues (Detail)	12 Months Ended
	Mar. 31, 2019 USD ($)
Change In Contract With Customer Liability [Abstract]
Beginning balance at April 1, 2018 (Note 5)	$ 15,316,000
Additions	28,938,000
Revenue recognized from beginning of period	(16,372,000)
Revenue recognized from additions	(10,982,000)
Ending balance at March 31, 2019 (Note 5)	$ 16,900,000