Balance Sheet Account Detail - Summary of Cash and Cash Equivalents and Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Cash and cash equivalents, Marketable securities, Cost	$ 126,673	$ 133,248
Cash and cash equivalents, Marketable securities, Gross Unrealized Gains	0	0
Cash and cash equivalents, Marketable securities, Gross Unrealized Losses	0	0
Cash and cash equivalents, Marketable securities, Estimated fair Value	126,673	133,248
Cash and cash equivalents	123,365	129,942	117,734	156,306
Marketable Security, Current	3,308	3,306
Bank Deposits [Member]
Schedule of Investments [Line Items]
Bank deposits, Cost	56,395	62,997
Bank deposits, Gross Unrealized Gains	0	0
Bank deposits, Gross Unrealized Losses	0	0
Bank deposits, Estimated fair Value	56,395	62,997
Cash and cash equivalents	56,395	62,997
Money market funds [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	66,970	66,945
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	66,970	66,945
Cash and cash equivalents	66,970	66,945
Bank CDs [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	246	244
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	246	244
Marketable Security, Current	246	244
Mutual Fund [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	3,062	3,062
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	3,062	3,062
Marketable Security, Current	$ 3,062	$ 3,062