Cash, Cash Equivalents, and Short-Term Investments - Summary of Cash, Cash Equivalents and Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	$ 70,748	$ 76,705
Cash and cash equivalents, Gross Unrealized Gains
Cash and cash equivalents, Gross Unrealized Losses	1	1
Cash and cash equivalents, Fair Value	70,747	76,704
Short-term investments, Amortized Cost	35,156	38,373
Short-term investments, Gross Unrealized Gains	22	22
Short-term investments, Gross Unrealized Losses	11	14
Short-term investments, Estimated Fair Value	35,167	38,381	[1]
Commercial paper [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	20,600	21,948
Cash and cash equivalents, Gross Unrealized Gains
Cash and cash equivalents, Gross Unrealized Losses	1	1
Cash and cash equivalents, Fair Value	20,599	21,947
Short-term investments, Amortized Cost	1,004
Short-term investments, Gross Unrealized Gains	1
Short-term investments, Gross Unrealized Losses
Short-term investments, Estimated Fair Value	1,005
Corporate debt obligations [Member]
Schedule of Investments [Line Items]
Short-term investments, Amortized Cost	23,908	28,220
Short-term investments, Gross Unrealized Gains	21	22
Short-term investments, Gross Unrealized Losses	11	14
Short-term investments, Estimated Fair Value	23,918	28,228
Bank deposits [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	10,180	10,165
Cash and cash equivalents, Gross Unrealized Gains
Cash and cash equivalents, Gross Unrealized Losses
Cash and cash equivalents, Fair Value	10,180	10,165
Short-term investments, Amortized Cost	10,244	10,153
Short-term investments, Gross Unrealized Gains
Short-term investments, Gross Unrealized Losses
Short-term investments, Estimated Fair Value	10,244	10,153
Cash [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	32,595	41,973
Cash and cash equivalents, Gross Unrealized Gains
Cash and cash equivalents, Gross Unrealized Losses
Cash and cash equivalents, Fair Value	32,595	41,973
Money market funds [Member]
Schedule of Investments [Line Items]
Cash and cash equivalents, Amortized Cost	7,373	2,619
Cash and cash equivalents, Gross Unrealized Gains
Cash and cash equivalents, Gross Unrealized Losses
Cash and cash equivalents, Fair Value	$ 7,373	$ 2,619

[1] The Condensed Consolidated Balance Sheet as of December 31, 2013 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.