Stockholders' Equity and Derivative Liability - Warrants - Common Stock and Warrant Offering (Details)					6 Months Ended	12 Months Ended
	Jul. 03, 2018 USD ($) $ / shares	Apr. 25, 2017 USD ($) $ / shares shares	Apr. 04, 2016 USD ($) $ / shares shares	Oct. 13, 2015 USD ($) $ / shares $ / item shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Jun. 30, 2017 shares
Common Stock and Warrant Offering
Underwriting discount and other offering expenses payable	$ 900,000
Derivative financial instruments liability - warrants					$ 669,462	$ 404,337	$ 669,462
Level 3 | Warrants
Common Stock and Warrant Offering
Derivative financial instruments liability - warrants					$ 700,000	$ 400,000	$ 700,000
Over-Allotment Option
Common Stock and Warrant Offering
Price of ContraVir common stock | $ / shares	$ 1.71
October 13 2015
Common Stock and Warrant Offering
Sale of shares (in shares) | shares				625,000
Fixed combined price (in dollars per share) | $ / shares				$ 24.00
Gross proceeds				$ 15,000,000
Underwriting discount and other offering expenses payable				1,500,000
Additional proceeds if warrants exercised in full				$ 12,800,000
Price of ContraVir common stock | $ / shares					$ 2.88	$ 0.28	$ 2.88
Expected warrant term (years)						1 year 9 months 11 days	2 years 9 months 11 days
Risk-free interest rate (as a percent)						2.48%	2.09%
Expected volatility (as a percent)						74.00%	67.00%
October 13 2015 | Warrants
Common Stock and Warrant Offering
Warrants issued (in shares) | shares				375,000
Exercise period for warrants				5 years
Exercise price of warrants (in dollars per share) | $ / shares				$ 34.00
October 13 2015 | Level 3 | Warrants
Common Stock and Warrant Offering
Derivative financial instruments liability - warrants				$ 4,400,000
October 13 2015 | Over-Allotment Option
Common Stock and Warrant Offering
Underwriter option period				45 days
Authorized for sale (in shares) | shares				93,750
Purchase price (in dollars per unit) | $ / item				24.00
October 13 2015 | Over-Allotment Option | Warrants
Common Stock and Warrant Offering
Number of warrants offered for sale | shares				56,250
April 4 2016
Common Stock and Warrant Offering
Sale of shares (in shares) | shares			616,197
Fixed combined price (in dollars per share) | $ / shares			$ 11.36
Gross proceeds			$ 7,000,000
Underwriting discount and other offering expenses payable			700,000
Additional proceeds if warrants exercised in full			$ 4,200,000
Price of ContraVir common stock | $ / shares					2.88	$ 0.28	$ 2.88
Expected warrant term (years)						2 years 3 months 4 days	3 years
Risk-free interest rate (as a percent)						2.48%	2.09%
Expected volatility (as a percent)						74.00%	67.00%
April 4 2016 | Warrants
Common Stock and Warrant Offering
Warrants issued (in shares) | shares			308,098
Exercise period for warrants			5 years
Exercise price of warrants (in dollars per share) | $ / shares			$ 13.60
April 4 2016 | Level 3 | Warrants
Common Stock and Warrant Offering
Derivative financial instruments liability - warrants			$ 1,500,000
April 25 2017
Common Stock and Warrant Offering
Sale of shares (in shares) | shares		1,500,000
Fixed combined price (in dollars per share) | $ / shares		$ 8.00
Gross proceeds		$ 12,000,000
Underwriting discount and other offering expenses payable		500,000
Additional proceeds if warrants exercised in full		$ 7,500,000
Price of ContraVir common stock | $ / shares					$ 2.88	$ 0.28	$ 2.88
Expected warrant term (years)						3 years 3 months 22 days	4 years
Risk-free interest rate (as a percent)						2.46%	2.09%
Expected volatility (as a percent)						74.00%	68.00%
April 25 2017 | Warrants
Common Stock and Warrant Offering
Warrants issued (in shares) | shares		750,000
Exercise period for warrants		5 years
Exercise price of warrants (in dollars per share) | $ / shares		$ 10.00
April 25 2017 | Level 3 | Warrants
Common Stock and Warrant Offering
Derivative financial instruments liability - warrants		$ 4,000,000
July 3 2018
Common Stock and Warrant Offering
Price of ContraVir common stock | $ / shares	$ 1.36					$ 0.28
Expected warrant term (years)	5 years					4 years 6 months
Risk-free interest rate (as a percent)	2.72%					2.51%
Expected volatility (as a percent)	75.00%					74.00%
Common Stock
Common Stock and Warrant Offering
Sale of shares (in shares) | shares					329,078			2,305,235