Description of Business - Additional Information (Detail)		12 Months Ended
	Mar. 01, 2017 shares	Dec. 31, 2017 USD ($) shares	Dec. 13, 2017 shares	Jun. 29, 2017 USD ($)	Dec. 31, 2016 USD ($) shares	Sep. 30, 2016 shares	Dec. 31, 2015 USD ($)	Jan. 01, 2015 USD ($)
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Accumulated deficit		$ (2,854,898,000)			$ (2,737,565,000)
Cash and cash equivalents		43,946,000			$ 22,895,000
Principal amount of outstanding borrowings		$ 157,800,000
Stock split of common stock	0.2
Reverse stock split, description		The Company’s board of directors approved a 1-for-5 reverse stock split of its outstanding common stock. On March 1, 2017, the Company filed with the Secretary of State of the State of Delaware a Certificate of Amendment of the Company’s Amended and Restated Certificate of Incorporation (the “Charter Amendment”) to effect the 1-for-5 reverse stock split of the Company’s outstanding common stock (the “Reverse Stock Split”) and to reduce the authorized number of shares of the Company’s common stock from 700,000,000 to 140,000,000 shares. The Company’s common stock began trading on the NASDAQ Global Market on a split-adjusted basis when the market opened on March 3, 2017. As a result, all common stock share amounts included in these consolidated financial statements have been retroactively reduced by a factor of five, and all common stock per share amounts have been increased by a factor of five, with the exception of the Company’s common stock par value.
Common stock, shares authorized | shares	140,000,000	280,000,000	280,000,000		140,000,000	700,000,000
Common stock		$ 1,192,000			$ 957,000
Additional paid-in capital		2,638,992,000			2,553,039,000
Adjustments
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock					(3,800,000)		$ (3,400,000)	$ (3,200,000)
Additional paid-in capital					3,800,000		$ 3,400,000	$ 3,200,000
Maximum
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock, shares authorized | shares			280,000,000
Minimum
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock, shares authorized | shares			140,000,000
Senior convertible notes due December 31, 2019 | Less portion of commitment asset
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Principal amount of outstanding borrowings		$ 54,407,000			$ 75,000,000
Deerfield | Less portion of commitment asset
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Senior notes, effective interest rate					8.75%
Deerfield | Senior convertible notes due December 31, 2019
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Senior notes, effective interest rate		9.75%
Principal amount of outstanding borrowings		$ 39,400,000			$ 55,000,000
Deerfield | Senior convertible notes due December 31, 2019 | Less portion of commitment asset
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Senior notes, effective interest rate		8.75%
Principal amount of outstanding borrowings		$ 15,000,000			$ 20,000,000
Deerfield | Senior convertible notes due December 31, 2019 | Minimum | Less portion of commitment asset
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Available amount of credit facility under covenant restrictions		$ 25,000,000
Deerfield | Senior convertible notes due December 31, 2019 | Minimum | Less portion of commitment asset | Third Amendment [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Available amount of credit facility under covenant restrictions				$ 10,000,000