Balance Sheet Components - Summary of Gross Unrealized Gains and Unrealized Losses of Investment Securities Excluding Investments in Money Market Funds (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 245,391	$ 139,691
Gross Unrealized Holding Gains	11	132
Gross Unrealized Holding Losses	(175)
Aggregate Fair Value	245,227	139,823
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	171,352	129,075
Gross Unrealized Holding Gains	9	131
Gross Unrealized Holding Losses	(103)
Aggregate Fair Value	171,258	129,206
Corporate Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	74,039
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses	(72)
Aggregate Fair Value	$ 73,969
Treasury Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		10,616
Gross Unrealized Holding Gains		1
Aggregate Fair Value		$ 10,617

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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