Fair Value Measurements - Schedule of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 56,967	$ 56,966
Short-term Investments, Gross Unrealized Holding Gains	13	10
Short-term Investments, Gross Unrealized Holding Losses	0	0
Short-term Investments, Fair Value	56,980	56,976
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments, Amortized Cost	56,967	56,966
Short-term Investments, Gross Unrealized Holding Gains	13	10
Short-term Investments, Gross Unrealized Holding Losses	0	0
Short-term Investments, Fair Value	$ 56,980	$ 56,976