Marketable Securities and Fair Value Measurements - Summary of Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 54,672	$ 64,726
Gross Unrealized Gains	292	13
Gross Unrealized Losses	0	(144)
Estimated Fair Value	54,964	64,595
U.S. treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	54,172	64,226
Gross Unrealized Gains	281	9
Gross Unrealized Losses	0	(144)
Estimated Fair Value	54,453	64,091
Mutual funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	500	500
Gross Unrealized Gains	11	4
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 511	$ 504

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=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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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
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-Section 50
-Paragraph 2
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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