Significant Balance Sheet Components - Accrued Expenses (Details) - USD ($)	1 Months Ended	3 Months Ended
	Oct. 31, 2017	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accrued Expenses [Abstract]
Accrued commissions			$ 5,327,000	$ 5,908,000
Accrued stock settled bonus			6,088,000	6,608,000
Accrued vacation			787,000	611,000
Employee stock purchase plan liability			838,000	1,811,000
Other accrued payroll-related expenses			2,706,000	3,085,000
Other accrued liabilities			6,706,000	3,651,000
Total accrued expenses			22,452,000	$ 21,674,000
Severance and bonus in conjunction with chief executive officer’s termination	$ 963,000
Bonus earned, in conjunction with chief executive officer’s termination and included in other accrued payroll-related expenses			$ 367,000
Severance costs in conjunction with chief executive officer’s termination		$ 596,000