Fair Value Disclosures - Schedule of Short-Term Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 39,933	$ 42,980
Short-term Investments, Gross Unrealized Holding Gains	0	1
Short-term Investments, Gross Unrealized Holding Losses	(15)	0
Short-term Investments, Fair Value	$ 39,918	$ 42,981
Available-for-sale securities, maturity period	1 year	1 year
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 39,933	$ 42,980
Short-term Investments, Gross Unrealized Holding Gains	0	1
Short-term Investments, Gross Unrealized Holding Losses	(15)	0
Short-term Investments, Fair Value	$ 39,918	$ 42,981