Borrowings - Additional Information (Detail)					3 Months Ended		9 Months Ended
	Oct. 23, 2017 USD ($) d $ / shares	Jun. 29, 2017 USD ($) $ / shares shares	Apr. 18, 2017 USD ($) $ / shares shares	Aug. 10, 2015 d $ / shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jul. 01, 2013 USD ($)
Debt Instrument [Line Items]
Loss on extinguishment of debt							$ 830,000
Cash and cash equivalents					$ 20,092,000	$ 35,530,000	20,092,000	$ 35,530,000	$ 22,895,000	$ 59,074,000
Facility Agreement, total principle payment in 2017					10,000,000		10,000,000
Facility Agreement, total principle payment in 2018					20,000,000		20,000,000
Facility Agreement, total principle payment in 2019					30,000,000		30,000,000
Other liabilities					103,400,000		103,400,000		123,200,000
Milestone Rights Liability
Debt Instrument [Line Items]
Other liabilities					18,700,000		$ 18,700,000		18,400,000
Deerfield
Debt Instrument [Line Items]
Principal repayment schedule, start date							Jul. 01, 2016
Principal repayment schedule, end date							Dec. 09, 2019
Deerfield | Milestone Rights Liability
Debt Instrument [Line Items]
Long term liability					8,900,000		$ 8,900,000
Deerfield | Milestone Rights Liability | Maximum
Debt Instrument [Line Items]
Contingent liability for milestone payments					90,000,000		90,000,000				$ 90,000,000
Senior convertible notes due December 31, 2019
Debt Instrument [Line Items]
Exchange price per share | $ / shares		$ 1.45	$ 1.22
Loss on extinguishment of debt		$ 500,000
Cash repayment			$ 4,000,000
Debt extinguishment amount		5,000,000
Debt discount and issuance costs		300,000
Debt facility principal amount					60,000,000		60,000,000		75,000,000
Carrying value					57,942,000		57,942,000		71,339,000
Senior convertible notes due December 31, 2019 | Less portion of commitment asset
Debt Instrument [Line Items]
Loss on extinguishment of debt			300,000
Senior convertible notes due December 31, 2019 | Deerfield
Debt Instrument [Line Items]
Debt facility principal amount					$ 45,000,000		$ 45,000,000
Senior notes, effective interest rate					9.75%		9.75%
Accrued expenses					$ 1,600,000		$ 1,600,000
Other current liabilities					1,600,000		1,600,000
Other liabilities					8,900,000		8,900,000		8,900,000
Senior convertible notes due December 31, 2019 | Deerfield | Facility Agreement Third Amendment [Member]
Debt Instrument [Line Items]
Cash repayment of senior notes under exchange agreement		10,000,000
Conversion of notes to common shares, value		$ 5,000,000
Conversion Option, shares | shares		3,584,230
Exchange price per share | $ / shares		$ 1.395
Cash and cash equivalents		$ 10,000,000
Senior convertible notes due December 31, 2019 | Deerfield | Minimum | Facility Agreement Third Amendment [Member]
Debt Instrument [Line Items]
Cash and cash equivalents		$ 25,000,000			10,000,000		10,000,000
Senior convertible notes due December 31, 2019 | Deerfield | Less portion of commitment asset
Debt Instrument [Line Items]
Cash repayment of senior notes under exchange agreement			4,000,000
Conversion of notes to common shares, value			$ 1,000,000
Debt facility principal amount					$ 15,000,000		$ 15,000,000
Senior notes, effective interest rate					8.75%		8.75%
Senior convertible notes due December 31, 2019 | Deerfield | Less portion of commitment asset | Facility Agreement
Debt Instrument [Line Items]
Available amount of credit facility under covenant restrictions					$ 10,000,000		$ 10,000,000
Senior convertible notes due December 31, 2019 | Deerfield | Less portion of commitment asset | Minimum
Debt Instrument [Line Items]
Available amount of credit facility under covenant restrictions					25,000,000		25,000,000
Senior convertible notes due December 31, 2019 | Deerfield | Less portion of commitment asset | Minimum | Facility Agreement
Debt Instrument [Line Items]
Available amount of credit facility under covenant restrictions					25,000,000		25,000,000
Senior convertible notes due December 31, 2019 | Deerfield | Tranche B Exchange Shares
Debt Instrument [Line Items]
Conversion Option, shares | shares			869,565
Exchange price per share | $ / shares			$ 1.15
Senior convertible notes due December 31, 2019 | Deerfield | Tranche 1 Notes
Debt Instrument [Line Items]
Conversion of notes to common shares, value			$ 5,000,000
Conversion Option, shares | shares			4,347,826
Senior convertible notes due December 31, 2019 | Deerfield | Milestone Rights Liability
Debt Instrument [Line Items]
Long term liability					7,200,000		7,200,000		8,900,000
Senior convertible notes due December 31, 2019 | Deerfield | Milestone Rights Liability | Assets Including Property and Equipment
Debt Instrument [Line Items]
Carrying value					27,400,000		27,400,000
5.75% Senior convertible notes due August 15, 2018
Debt Instrument [Line Items]
Debt discount and issuance costs					70,000	$ 65,000	204,000	$ 190,000
Debt facility principal amount					27,690,000		27,690,000		27,690,000
Senior notes, effective interest rate				5.75%
Carrying value					27,657,000		$ 27,657,000		$ 27,635,000
No of convertible shares				29
Principal amount per share | $ / shares				$ 1,000
Percentage of repurchase price				100.00%
Debt Instrument, redemption description							On or after the date that is one year following the original issue date of the 2018 notes, the Company would have had the right to redeem for cash all or part of the 2018 notes if the last reported sale price of its common stock exceeds 130% of the conversion price then in effect for 20 or more trading days during the 30 consecutive trading day period ending on the trading day immediately prior to the date of the redemption notice. The redemption price was equal the sum of 100% of the principal amount of the 2018 notes to be redeemed, plus accrued and unpaid interest.
Percentage of conversion price equaling stock price				130.00%
Number of trading days | d				20
Consecutive trading days				30 days
Debt Issuance Cost					$ 800,000		$ 800,000
5.75% Senior convertible notes due August 15, 2018 | Subsequent Event
Debt Instrument [Line Items]
Debt facility principal amount	$ 27,690,000
5.75% Senior convertible notes due October 23, 2021 | Subsequent Event
Debt Instrument [Line Items]
Debt facility principal amount	$ 23,690,000
Senior notes, effective interest rate	5.75%
No of convertible shares	194.1748
Principal amount per share | $ / shares	$ 1,000
Percentage of repurchase price	100.00%
Percentage of conversion price equaling stock price	120.00%
Number of trading days | d	10