Short-Term Marketable Securities - Summary of Short-Term Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 23,266	$ 23,511
Unrealized Gain	0	0
Unrealized Loss	8	12
Market Value	23,258	23,499
U.S. treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,027	5,558
Unrealized Gain	0	0
Unrealized Loss	8	1
Market Value	7,019	5,557
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000	2,025
Unrealized Gain	0	0
Unrealized Loss	0	5
Market Value	1,000	2,020
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,239	8,429
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	$ 15,239	8,429
Government-sponsored enterprise securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		7,499
Unrealized Gain		0
Unrealized Loss		6
Market Value		$ 7,493