Fair Value of Financial Instruments - Assets Measured or Disclosed at Fair Value on Recurring Basis (Detail) (USD $)
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Dec. 31, 2014
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Dec. 31, 2013
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
$ 108,918,147us-gaap_AssetsFairValueDisclosure |
$ 32,556,469us-gaap_AssetsFairValueDisclosure |
Level 1 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
32,780,113us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
21,215,228us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
Level 2 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
76,138,034us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
11,341,241us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
Level 3 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
0us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
0us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
Cash and cash equivalents |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
32,780,113us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CashAndCashEquivalentsMember |
21,215,228us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CashAndCashEquivalentsMember |
Cash and cash equivalents | Level 1 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
32,780,113us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
21,215,228us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
Certificates of deposit |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
13,429,004us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CertificatesOfDepositMember |
1,330,132us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CertificatesOfDepositMember |
Certificates of deposit | Level 2 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
13,429,004us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CertificatesOfDepositMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
1,330,132us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CertificatesOfDepositMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
U.S. Government debt securities |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
38,385,287us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_USGovernmentDebtSecuritiesMember |
7,509,369us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_USGovernmentDebtSecuritiesMember |
U.S. Government debt securities | Level 2 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
38,385,287us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_USGovernmentDebtSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
7,509,369us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_USGovernmentDebtSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
Commercial Paper |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
2,499,264us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CommercialPaperMember |
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Commercial Paper | Level 2 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
2,499,264us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CommercialPaperMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
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Corporate debt securities |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
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Assets Measured at fair value on recurring basis |
21,824,479us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CorporateDebtSecuritiesMember |
2,501,740us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CorporateDebtSecuritiesMember |
Corporate debt securities | Level 2 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
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Assets Measured at fair value on recurring basis |
$ 21,824,479us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
$ 2,501,740us-gaap_AssetsFairValueDisclosure / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |