Fair Value Measurements - Schedule of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments, Amortized Cost	$ 56,969	$ 56,966
Short-term Investments, Gross Unrealized Holding Gains	11	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	56,969	56,966
Short-term Investments, Gross Unrealized Holding Gains	11	10
Short-term Investments, Gross Unrealized Holding Losses	0	0
Short-term Investments, Fair Value	$ 56,980	$ 56,976