Balance Sheet Account Detail - Summary of Cash and Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Cash and cash equivalents, Marketable securities, Cost	$ 139,986	$ 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	139,986	133,248
Cash and cash equivalents	139,741	129,942	$ 156,306	$ 139,698
Marketable Security, Current	245	3,306
Bank Deposits [Member]
Schedule of Investments [Line Items]
Bank deposits, Cost	59,625	62,997
Bank deposits, Gross Unrealized Gains	0	0
Bank deposits, Gross Unrealized Losses	0	0
Bank deposits, Estimated fair Value	59,625	62,997
Cash and cash equivalents	59,625	62,997
Money Market Funds [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	80,116	66,945
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	80,116	66,945
Cash and cash equivalents	80,116	66,945
Bank CDs [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	245	244
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	245	244
Marketable Security, Current	$ 245	244
Mutual Funds [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost		3,062
Marketable security, Gross Unrealized Gains		0
Marketable security, Gross Unrealized Losses		0
Marketable security, Estimated fair Value		3,062
Marketable Security, Current		$ 3,062