Balance Sheet Components - Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 5,005
Fair Value	5,005
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,497	$ 12,882
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(15)
Fair Value	4,497	12,867
Short-term Investments [Member] \| U.S. Agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	750	1,551
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(2)
Fair Value	750	1,549
Short-term Investments [Member] \| U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	500
Short-term Investments [Member] \| Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,747	7,776
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(13)
Fair Value	3,747	7,763
Short-term Investments [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	500
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	500
Short-term Investments [Member] \| Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	2,555
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	2,555
Long-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	508	3,496
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(6)
Fair Value	508	3,490
Long-term Investments [Member] \| U.S. Agency securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	499
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(2)
Fair Value	0	497
Long-term Investments [Member] \| U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		0
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		0
Long-term Investments [Member] \| Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	263	878
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(4)
Fair Value	263	874
Long-term Investments [Member] \| Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	245	2,119
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 245	$ 2,119

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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