Common Stock and Stockholders' Equity - Narrative (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2014	Jun. 30, 2019	Jun. 30, 2018
Class of Stock [Line Items]
Stock-based compensation expense		$ 21,188	$ 11,027
Unrecognized stock-based compensation cost related to outstanding unvested stock awards		$ 28,600
Stock-based compensation cost expected to be recognized over weighted-average period		2 years 8 months 12 days
Expected to vest unrecognized stock-based compensation cost related to outstanding unvested stock options		$ 177,400
Unvested Stock Options
Class of Stock [Line Items]
Stock based compensation cost is expected to be recognized over a weighted-average period		2 years 9 months 18 days
ESPP shares
Class of Stock [Line Items]
Shares reserved for issuance under plan (in shares)	1,000,000
Additional shares available for issuance under the plan (in shares)	500,000
Percentage of common stock shares increased under the plan	1.00%
Stock-based compensation expense		$ 1,200	$ 400
Shares available for issuance (in shares)		2,773,989
2008 Equity Incentive Plan
Class of Stock [Line Items]
Shares available for issuance (in shares)		0
2014 Equity Incentive Plan
Class of Stock [Line Items]
Shares reserved for issuance under plan (in shares)	5,000,000
Shares available for issuance (in shares)		13,348,169
Shares available for grant under plan (in shares)	5,184,878
Increase in shares available under plan, percentage of outstanding common stock shares	5.00%