Balance Sheet Account Detail - Summary of Cash and Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Cash and cash equivalents, Marketable securities, Cost	$ 158,469	$ 139,986
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	158,469	139,986
Cash and cash equivalents	158,222	139,741	$ 129,942	$ 156,306
Marketable Security, Current	247	245
Bank Deposits [Member]
Schedule of Investments [Line Items]
Bank deposits, Cost	23,915	59,625
Bank deposits, Gross Unrealized Gains	0	0
Bank deposits, Gross Unrealized Losses	0	0
Bank deposits, Estimated fair Value	23,915	59,625
Cash and cash equivalents	23,915	59,625
Money Market Funds [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	128,563	80,116
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	128,563	80,116
Cash and cash equivalents	128,563	80,116
Bank CDs [Member]
Schedule of Investments [Line Items]
Marketable security, Amortized Cost	5,991	245
Marketable security, Gross Unrealized Gains	0	0
Marketable security, Gross Unrealized Losses	0	0
Marketable security, Estimated fair Value	5,991	245
Cash and cash equivalents	5,744	0
Marketable Security, Current	$ 247	$ 245