Net Income (Loss) per Share - Reconciliation of Basic and Diluted Shares (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted average number of shares outstanding:
Basic	33,724	32,284	29,849
Dilutive effects of:
Employee stock options, RSU’s and share based payment awards issued to employees	514	0	0
Diluted	34,238	32,284	29,849