Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Cash equivalents maturity period	3 months
Short-term investments maturity period	90 days
Period of royalties notification, minimum	30 days
Period of royalties notification, maximum	45 days
Advertising expense	$ 102,000	$ 265,000	$ 344,000
Cost capitalized	$ 0
Period of maturities, money market and highly liquid debt	90 days