Balance Sheet Components - Gains and Losses of Marketable Investments (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost		$ 48,625
Gross unrealized gains		7
Gross unrealized losses		(379)
Fair value	$ 0	48,253
Realized loss on sale of marketable investments	$ 500
U.S. Agency securities
Schedule of Available-for-sale Securities [Line Items]
Cost		6,012
Gross unrealized gains		3
Gross unrealized losses		(9)
Fair value		6,006
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Cost		4,011
Gross unrealized gains		0
Gross unrealized losses		(2)
Fair value		4,009
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Cost		29,834
Gross unrealized gains		4
Gross unrealized losses		(219)
Fair value		29,619
Mutual funds
Schedule of Available-for-sale Securities [Line Items]
Cost		8,768
Gross unrealized gains		0
Gross unrealized losses		(149)
Fair value		$ 8,619

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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

+ References

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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+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

+ References

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-Publisher FASB

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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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