Balance Sheet Account Detail - Summary of Cash and Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Cash and cash equivalents, Marketable securities, Cost	$ 132,552	$ 139,986
Cash and cash equivalents, Marketable securities, Gross Unrealized Gains	0	0
Cash and cash equivalents, Marketable securities, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	45
Cash and cash equivalents, Marketable securities, Estimated fair Value	132,552	139,986
Cash and cash equivalents	132,306	139,741	$ 123,365	$ 129,942
Marketable Security, Current	246	245
Bank Deposits [Member]
Schedule of Investments [Line Items]
Bank deposits, Cost	52,160	59,625
Bank deposits, Gross Unrealized Gains	0	0
Bank deposits, Gross Unrealized Losses	0	0
Bank deposits, Estimated fair Value	52,160	59,625
Cash and cash equivalents	52,160	59,625
Money market funds [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	80,146	80,116
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	80,146	80,116
Cash and cash equivalents	80,146	80,116
Bank CDs [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	246	245
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	246	245
Marketable Security, Current	246	245
Mutual Fund [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	0	0
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	0	0
Marketable Security, Current	$ 0	$ 0