Annual report pursuant to Section 13 and 15(d)

Warrants (Schedule Of Assumptions Used In Calculating Fair Value Of Warrants) (Details)

v2.4.1.9
Warrants (Schedule Of Assumptions Used In Calculating Fair Value Of Warrants) (Details) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
June 5, 2009 Warrants [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices    $ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Estimated future volatility   109.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Estimated future risk-free rate    0.13%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Equivalent volatility, minimum   43.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Equivalent volatility, maximum   45.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Equivalent risk-free rate, minimum   0.05%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
Equivalent risk-free rate, maximum   0.06%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateBWarrantsMember
October 23, 2009 Warrants To Institutional Investors [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices    $ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateCWarrantsToInstitutionalInvestorsMember
Estimated future volatility    109.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateCWarrantsToInstitutionalInvestorsMember
Estimated future risk-free rate    0.13%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateCWarrantsToInstitutionalInvestorsMember
Equivalent volatility    57.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateCWarrantsToInstitutionalInvestorsMember
Equivalent risk-free rate    0.07%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateCWarrantsToInstitutionalInvestorsMember
June 30, 2010 Warrants To Institutional Investors [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices    $ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateDWarrantsToInstitutionalInvestorsMember
Estimated future volatility    109.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateDWarrantsToInstitutionalInvestorsMember
Estimated future risk-free rate    0.13%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateDWarrantsToInstitutionalInvestorsMember
Equivalent volatility    49.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateDWarrantsToInstitutionalInvestorsMember
Equivalent risk-free rate    0.06%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateDWarrantsToInstitutionalInvestorsMember
March 31, 2011 Warrants To Institutional Investors [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices $ 0.70rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember 		$ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember
Estimated future volatility 108.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember 		109.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember
Estimated future risk-free rate 0.91%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember 		1.58%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember
Equivalent volatility 67.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember 		71.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember
Equivalent risk-free rate 0.22%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember 		0.27%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateEWarrantsToInstitutionalInvestorsMember
December 4, 2012 Warrants [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices $ 0.70rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		$ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Estimated future volatility 108.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		109.00%rnn_InvestmentWarrantsFairValueAssumptionsEstimatedFutureVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Estimated future risk-free rate, minimum 0.74%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		1.58%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Estimated future risk-free rate, maximum 1.90%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		2.72%rnn_InvestmentWarrantsFairValueAssumptionsRiskFreeInterestRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Equivalent volatility, minimum 65.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		69.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Equivalent volatility, maximum 71.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		73.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Equivalent risk-free rate, minimum 0.18%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		0.22%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
Equivalent risk-free rate, maximum 0.43%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember 		0.40%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateFWarrantsMember
July 26, 2013 Warrants [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices $ 0.70rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember 		$ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember
Equivalent volatility, minimum 65.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember 		69.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember
Equivalent volatility, maximum 74.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember 		77.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember
Equivalent risk-free rate, minimum 0.18%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember 		0.22%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember
Equivalent risk-free rate, maximum 0.55%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember 		0.62%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateGWarrantsMember
October 16, 2013 Warrants [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices $ 0.70rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember 		$ 0.51rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember
Equivalent volatility, minimum 65.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember 		69.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember
Equivalent volatility, maximum 75.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember 		76.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember
Equivalent risk-free rate, minimum 0.18%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember 		0.20%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMinimum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember
Equivalent risk-free rate, maximum 0.59%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember 		0.52%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRateMaximum
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateHWarrantsMember
January 21, 2014 Warrants To Institutional Investors [Member]    
Class of Warrant or Right [Line Items]    
Trading market prices $ 0.70rnn_InvestmentWarrantsFairValueAssumptionsTradingMarketPrices
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateIWarrantsToInstitutionalInvestorsMember 		  
Equivalent volatility 78.00%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentVolatilityRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateIWarrantsToInstitutionalInvestorsMember 		  
Equivalent risk-free rate 0.63%rnn_InvestmentWarrantsFairValueAssumptionsEquivalentRiskFreeRate
/ us-gaap_ClassOfWarrantOrRightAxis
= rnn_DateIWarrantsToInstitutionalInvestorsMember