Investments and Fair Value of Financial Instruments - Summary of Amortized Cost and Fair Value of the Available-For-Sale Investment Securities Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 60,410	$ 67,930
Unrealized Gains	6	1
Unrealized Losses	(12)	(116)
Estimated Fair Value	60,404	67,815
Cash Equivalents [Member] \| Money Market Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	26,622	12,799
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	26,622	12,799
Cash Equivalents [Member] \| Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		5,949
Unrealized Gains		0
Unrealized Losses		0
Estimated Fair Value		5,949
Cash Equivalents [Member] \| U.S. Government Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		3,049
Unrealized Gains		0
Unrealized Losses		0
Estimated Fair Value		3,049
Short-term Investments [Member] \| Certificates of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	3,046	3,374
Unrealized Gains	0	0
Unrealized Losses	(4)	0
Estimated Fair Value	3,042	3,374
Short-term Investments [Member] \| U.S. Government Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	22,824	13,678
Unrealized Gains	5	0
Unrealized Losses	(1)	(30)
Estimated Fair Value	22,828	13,648
Short-term Investments [Member] \| Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		3,598
Unrealized Gains		0
Unrealized Losses		0
Estimated Fair Value		3,598
Short-term Investments [Member] \| U.S. Government Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,002	5,653
Unrealized Gains	0	1
Unrealized Losses	0	(4)
Estimated Fair Value	1,002	5,650
Long-term investments [Member] \| Certificates of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,916	3,049
Unrealized Gains	1	0
Unrealized Losses	(3)	0
Estimated Fair Value	1,914	3,049
Long-term investments [Member] \| U.S. Government Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		11,780
Unrealized Gains		0
Unrealized Losses		(52)
Estimated Fair Value		11,728
Long-term investments [Member] \| U.S. Government Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,000	5,001
Unrealized Gains	0	0
Unrealized Losses	(4)	(30)
Estimated Fair Value	$ 4,996	$ 4,971

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
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity 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 and equity securities classified as available-for-sale.

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