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Income Taxes - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Income Tax Disclosure [Abstract]    
Operating loss carryforwards, latest expiration year 2033  
Operating loss carryforwards, expiration date various years through 2033  
Increase in operating loss carryforwards $ 7,170,000isco_OperatingLossCarryforwardIncreaseDecrease  
Operating loss carryforwards 56,083,000us-gaap_OperatingLossCarryforwards 48,913,000us-gaap_OperatingLossCarryforwards
Net deferred tax asset recognized $ 0us-gaap_DeferredTaxAssetsNet $ 0us-gaap_DeferredTaxAssetsNet
Change period for unrecognized tax benefits 12 months