Common Stock and Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Shares of common stock reserved for future issuance (in shares)	18,240	16,799
RSUs outstanding
Class of Stock [Line Items]
Shares of common stock reserved for future issuance (in shares)	2,419	2,079
Available for future stock option and RSU grants
Class of Stock [Line Items]
Shares of common stock reserved for future issuance (in shares)	10,796	9,576
Available for future employee stock purchase plan awards
Class of Stock [Line Items]
Shares of common stock reserved for future issuance (in shares)	2,274	1,929
Common stock options outstanding
Class of Stock [Line Items]
Shares of common stock reserved for future issuance (in shares)	2,751	3,215