Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities (Narrative) (Details)

v2.4.1.9
Marketable Securities (Narrative) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Fair value $ 18,655,821us-gaap_AvailableForSaleSecurities $ 22,872,051us-gaap_AvailableForSaleSecurities
Unrealized losses 3,076us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax 33,769us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Certificates Of Deposit With Unrealized Losses [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in a loss position 18rnn_AvailableForSaleSecuritiesInLossPosition
/ us-gaap_InvestmentTypeAxis
= rnn_CertificatesOfDepositWithUnrealizedLossesMember 		 
Fair value 4,318,485us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= rnn_CertificatesOfDepositWithUnrealizedLossesMember 		 
Unrealized losses 1,515us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= rnn_CertificatesOfDepositWithUnrealizedLossesMember 		 
Corporate Bond With Unrealized Losses [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in a loss position 3rnn_AvailableForSaleSecuritiesInLossPosition
/ us-gaap_InvestmentTypeAxis
= rnn_CorporateBondSecuritiesWithUnrealizedLossesMember 		 
Fair value 2,534,100us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= rnn_CorporateBondSecuritiesWithUnrealizedLossesMember 		 
Unrealized losses $ 1,561us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= rnn_CorporateBondSecuritiesWithUnrealizedLossesMember