Summary of Restructuring Costs by Function (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	$ 3,651
Total restructuring expenses, Non-cash	911	[1]
Total restructuring expenses	4,562
Research and Development [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	1,631
Total restructuring expenses, Non-cash	382	[1]
Total restructuring expenses	2,013
Selling, General and Administrative [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	2,020
Total restructuring expenses, Non-cash	529	[1]
Total restructuring expenses	$ 2,549

[1] The non-cash restructuring expenses include the following: $0.8 million accelerated depreciation for certain assets $0.1 million acceleration of stock option vesting