Other Balance Sheet Amounts (Investments in Marketable Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Weighted-average Remaining Contractual Maturity	7 months 28 days
Available-for-sale - short-term:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 21,846	$ 23,271
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(1)	(22)
Fair Value	21,847	23,249
Available-for-sale - short-term: \| U.S. Treasury, government and agency debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,449	10,485
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(1)	(22)
Fair Value	15,450	10,463
Available-for-sale - short-term: \| Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,397	12,786
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	6,397	12,786
Available-for-sale - long-term: \| U.S. Treasury, government and agency debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,539	13,529
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	(46)
Fair Value	$ 8,534	$ 13,483

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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
-Subparagraph (aa)
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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