Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities (Schedule Of Cost And Fair Value By Contractual Maturity) (Details)

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Marketable Securities (Schedule Of Cost And Fair Value By Contractual Maturity) (Details) (USD $)
Mar. 31, 2015
Marketable Securities [Abstract]  
Less than 1 year, Cost Basis, Maturity $ 13,499,679rnn_AvailableForSaleSecuritiesDebtMaturitiesRemainingFiscalYearAmortizedCostBasis
Less than 1 year, Fair Value, Maturity 13,499,823rnn_AvailableForSaleSecuritiesDebtMaturitiesRemainingFiscalYearFairValue
1 to 5 years, Cost Basis, Maturity 5,155,066rnn_AvailableForSaleSecuritiesDebtMaturitiesYearOneThroughFiveAmortizedCostBasis
1 to 5 years, Fair Value, Maturity 5,155,998rnn_AvailableForSaleSecuritiesDebtMaturitiesYearOneThroughFiveFairValue
Total Marketable Securities, Cost Basis, Maturity 18,654,745us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Total Marketable Securities, Fair Value, Maturity $ 18,655,821us-gaap_AvailableForSaleSecuritiesDebtSecurities