Employee Stock Purchase Plan - Additional Information (Detail) - shares	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Employee Stock Purchase Plan [Line Items]
Percentage of employees contribution of their gross pay	20.00%
Stock issued under employee stock purchase plan, shares	2,469,843
Employee Stock Purchase Plan [Member]
Employee Stock Purchase Plan [Line Items]
Percentage as purchase price of closing sale price of shares	95.00%
Maximum shares authorized for issuance under the ESPP	2,850,000
Stock issued under employee stock purchase plan, shares	8,976	10,596	10,975