Restructuring Charges - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Mar. 31, 2018	Feb. 28, 2018	Sep. 30, 2017	Jan. 31, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring charges				$ 899
Subsequent Event
Restructuring Cost And Reserve [Line Items]
Board of directors approved percentage of restructuring and reduction in force plan	20.00%
205 Ravendale Drive, Mountain View, California | Subsequent Event
Restructuring Cost And Reserve [Line Items]
Lease termination, month and year		2018-02
Minimum
Restructuring Cost And Reserve [Line Items]
Board of directors approved percentage of restructuring and reduction in force plan			10.00%