Short Term Investments - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Securities Purchased Under Agreements to Resell and Other Short Term Investment Securities [Line Items]
Short-term investments	$ 42,952	$ 42,994
Weighted average interest rate on U.S. Treasury bills, maximum	1.00%	1.00%
US Treasury Bill Securities
Securities Purchased Under Agreements to Resell and Other Short Term Investment Securities [Line Items]
Short-term investments	$ 43,000	$ 43,000