Marketable Securities, Available for Sale - Summary of Available-for-Sale Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 14,626	$ 11,538
Unrealized Gain	2	3
Unrealized Loss	4	0
Market Value	14,624	11,541
U.S. treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,560	1,500
Unrealized Gain	2	3
Unrealized Loss	0	0
Market Value	3,562	1,503
Government-sponsored enterprise securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,998	4,500
Unrealized Gain	0	0
Unrealized Loss	4	0
Market Value	6,994	4,500
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	4,853
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	0	4,853
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,068	685
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	$ 4,068	$ 685