Annual report pursuant to Section 13 and 15(d)

Marketable Securities (Narrative) (Details)

v2.4.1.9
Marketable Securities (Narrative) (Details) (USD $)
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]  
Fair value $ 22,872,051us-gaap_AvailableForSaleSecurities
Unrealized losses 33,769us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Certificates Of Deposit With Unrealized Losses [Member]  
Schedule of Available-for-sale Securities [Line Items]  
Fair value 18,598,211us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= rnn_CertificatesOfDepositWithUnrealizedLossesMember
Unrealized losses 26,789us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= rnn_CertificatesOfDepositWithUnrealizedLossesMember
Commercial Paper With Unrealized Losses [Member]  
Schedule of Available-for-sale Securities [Line Items]  
Fair value 998,180us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= rnn_CommercialPaperWithUnrealizedLossesMember
Unrealized losses 153us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= rnn_CommercialPaperWithUnrealizedLossesMember
Corporate Bond With Unrealized Losses [Member]  
Schedule of Available-for-sale Securities [Line Items]  
Fair value 2,035,870us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= rnn_CorporateBondSecuritiesWithUnrealizedLossesMember
Unrealized losses $ 6,827us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= rnn_CorporateBondSecuritiesWithUnrealizedLossesMember