Acquisition and Stockholders' Equity (Deficit) (Details)						2 Months Ended	3 Months Ended		10 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Nov. 03, 2014 USD ($) $ / shares	Mar. 05, 2014 USD ($) $ / shares	Feb. 06, 2014 $ / shares	Jan. 28, 2014 shares	Mar. 04, 2014 USD ($) $ / shares shares	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) shares	Jul. 02, 2015 USD ($)	Jun. 08, 2015 shares	Mar. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)	Feb. 05, 2014 $ / shares
Acquisitions and Stockholders' Equity (Deficit)
Decrease in exercise price (in dollars per share) | $ / shares				$ 0.011
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001		$ 0.0001						$ 0.0001	$ 0.0001	$ 0.0001
Selling agent fees										$ 404,000	$ 846,000	$ 5,623,000
Gross proceeds from sale of common stock by the entity (in dollars)										14,672,000	$ 30,700,000	$ 94,734,000
Debt conversion amount										$ 40,989,000
Number of authorized shares of common stock | shares	350,000,000								350,000,000	350,000,000	350,000,000	200,000,000		350,000,000
Common stock issued in connection with exercise of stock options										$ 1,142,000	$ 36,000	$ 119,000
Proceeds from exercise of stock options										1,142,000	36,000	$ 119,000
Convertible Senior Notes Due 2019
Acquisitions and Stockholders' Equity (Deficit)
Aggregate principal amount (in dollars)	$ 159,011,000	$ 200,000,000					$ 159,011,000	$ 177,787,000	$ 200,000,000	159,011,000	$ 200,000,000				$ 200,000,000	$ 200,000,000
Interest rate (as a percent)		7.50%
Additional aggregate principal amount pertaining to the over-allotment option granted (in dollars)		$ 25,000,000
Conversion rate (as a percent)		0.3215434
Conversion price (in dollars per share) | $ / shares		$ 3.11
Net proceeds from offering (in dollars)		$ 187,300,000
Debt conversion amount							$ 18,776,000	$ 22,213,000		$ 41,000,000
Number of shares issued on conversion of debt | shares	51,128,938									13,200,000	64,308,680
June 2012 Amended Controlled Equity Offering Sales Agreement
Acquisitions and Stockholders' Equity (Deficit)
Additional aggregate offering price of common stock			$ 50,000,000
Selling agent fees			$ 3.0
Common stock issued (in shares) | shares						6,417,650			3,435,998
Gross proceeds from sale of common stock by the entity (in dollars)						$ 30,700,000			$ 14,700,000	$ 1,000,000
Average selling price (in dollars per share) | $ / shares						$ 4.78			$ 4.27
Attorney Fees Incurred						$ 800,000				$ 400,000
Warrants to purchase shares of common stock (in shares) | shares										189,412
Employee stock option exercised | shares										269,720
Common stock issued in connection with exercise of stock options										$ 1,100,000
Shelf Registration
Acquisitions and Stockholders' Equity (Deficit)
Aggregate principal amount (in dollars)													$ 250,000,000
ContraVir Subsidiary
Acquisitions and Stockholders' Equity (Deficit)
Shares approved for distribution | shares					9,000,000
Shares of subsidiary to be distributed for each share of the entity's shares outstanding | shares					0.0986
Public Company
Acquisitions and Stockholders' Equity (Deficit)
Warrants outstanding (in shares) | shares	4,726,823									4,726,823
Public Company | Weighted average
Acquisitions and Stockholders' Equity (Deficit)
Exercise price of warrants (in dollars per share) | $ / shares	$ 5.13									$ 5.13							$ 5.15