Stockholders' Deficit - Additional Information (Detail) - USD ($)	3 Months Ended
	May 31, 2016	Sep. 30, 2015
2015 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, offering period	6 months
Employee Stock Purchase Plan, percentage	85.00%
Number of common stock shares reserved for issuance (in shares)	715,230
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options and RSUs granted vesting period	4 years
Unrecognized compensation cost related to outstanding stock options	$ 15,600,000
Expected period for recognizing compensation expense	2 years 5 months 11 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options and RSUs granted vesting period	4 years
Expected period for recognizing compensation expense	3 years 10 days
Unrecognized compensation cost related to unvested RSUs	$ 53,200,000
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted are exercisable for periods	10 years
Common stock repurchase program, aggregate purchase price		$ 50,000,000
Maximum | 2015 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance (in shares)	750,000