Warrants - Issued April 4, 2014 Black Scholes (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair value assumptions and methodology for assets and liabilities
Number of warrants (in shares)	3,613,615	4,567,207
Warrants Issued April 4, 2014, Liability
Fair value assumptions and methodology for assets and liabilities
Number of warrants (in shares)	664,000	664,000
CDTi stock price (in dollars per share)	$ 0.72	$ 0.94
Strike price (in dollars per share)	$ 4.20	$ 4.20
Expected volatility	98.00%	94.40%
Risk-free interest rate	1.00%	1.50%
Expected life in years	3 years 6 months	3 years 9 months 18 days
Warrants Issued April 4, 2014, Liability | November 23, 2015 Offering
Fair value assumptions and methodology for assets and liabilities
Number of warrants (in shares)	148,000	148,000
CDTi stock price (in dollars per share)	$ 0.72	$ 0.94
Strike price (in dollars per share)	$ 1.70	$ 1.70
Expected volatility	95.20%	96.70%
Risk-free interest rate	1.10%	1.60%
Expected life in years	4 years 1 month 6 days	4 years 4 months 24 days