Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Denominator:
Weighted average common shares outstanding (in shares)	49,060	49,477	49,110	49,264
Less: shares of restricted stock subject to repurchase (in shares)	0	(2)	0	(3)
Total common shares-basic (in shares)	49,060	49,475	49,110	49,261
Effect of dilutive securities:
Options (in shares)	0	0	0	0
Restricted stock awards and units (in shares)	0	0	0	0
Total common shares-diluted (in shares)	49,060	49,475	49,110	49,261