Convertible Debt - Additional Information (Detail)		1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended
	Feb. 23, 2017 USD ($) d $ / shares	Mar. 31, 2016 USD ($) d shares	Dec. 31, 2013 USD ($) d	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) shares	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) shares	Mar. 21, 2016 USD ($)
Debt Instrument [Line Items]
Net product sales				$ 18,768,000	$ 5,241,000		$ 61,041,000	$ 8,176,000
Preferred stock, shares issued | shares				219,994			219,994			219,994
Fundamental change amount		$ 0				$ 0
Proceeds from issuance of Series Z Preferred						$ 3,300,000		$ 3,343,000
Gain on extinguishment of debt							$ 12,316,000
Baupost
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners		18.10%				18.10%
Series Z Preferred Stock
Debt Instrument [Line Items]
Preferred stock, shares issued | shares				219,994			219,994			219,994
Liquidation preference threshold exceeds amount received by holder of common stock		$ 975,000				$ 975,000
Liquidation preference does not exceeds amount received by holder of common stock		225,000				225,000
Liquidation preference threshold does not exceeds amount received by holder of common stock		$ 975,000				975,000
Preferred stock, expires, outstanding shares voted as a separate class, percentage		70.00%
0% Convertible Senior Secured Notes due 2020 (2016 Notes)
Debt Instrument [Line Items]
Debt instrument, principal amount		$ 165,000,000		$ 1,000		$ 165,000,000	$ 1,000				$ 165,000,000
Interest rate		0.00%		0.00%		0.00%	0.00%				0.00%
Warrants to purchase | shares		21,999,999				21,999,999
Debt instrument, maturity date		Jul. 01, 2020
Threshold trading days | d		35
Debt instrument, convertible, terms of conversion feature							The 2016 Notes shall only be convertible into shares of common stock of the Company at the conversion rate. In the event of a change of control transaction at any time, the 2016 Notes will be convertible for a period beginning on the closing of such change of control transaction and ending 35 trading days after the closing of such transaction.
Debt instrument, convertible, conversion rate							133.333
Debt instrument, convertible, conversion price | $ / shares				$ 7.50			$ 7.50
Minimum aggregate principal amount outstanding for declaration notice		25.00%				25.00%
Debt instrument, redemption price, percentage		100.00%
Debt instrument, redemption, description							the Company to repurchase for cash all or a portion of their 2016 Notes at a repurchase price equal to 100% of the aggregate principal amount of 2016 Notes. In particular, under the indenture an adverse event is deemed to occur if consolidated net product sales (a non-GAAP measure defined in the 2016 Indenture as the Company’s net sales plus aggregate net sales by the Company’s distributors outside the United States) are less than $100 million for fiscal year 2017, provided that the effective date of such adverse event would not be deemed to occur until June 30, 2018. The 2016 Notes were not redeemable by the Company, in whole or in part, prior to the receipt of the required stockholder approvals, or the Stockholder Approval, which the Company obtained at its 2016 annual meeting of stockholders in July 2016. From and after the receipt of the Stockholder Approval, the 2016 Notes are not redeemable, in whole or in part, without the consent of the holders of not less than 70% in aggregate principal amount of the 2016 Notes at the time outstanding.
Exercise price of warrants | $ / shares				$ 15.00			$ 15.00
Warrants expiration date							Sep. 21, 2026
Hybrid instrument, fair value		$ 120,000,000				$ 120,000,000
Unrealized loss on hybrid instrument, net		$ (45,000,000)
Fair value of liability component upon issuance				$ 129,200,000			$ 129,200,000
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Selling, General and Administrative
Debt Instrument [Line Items]
Upfront costs and fees										$ 5,300,000
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Maximum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		70.00%
Debt instrument, threshold percentage, principal amount outstanding		25.00%
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Debt Conversion Description 1
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Debt Conversion Description 2
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Scenario Forecast | Maximum
Debt Instrument [Line Items]
Net product sales									$ 100,000,000
0% Convertible Senior Secured Notes due 2020 (2016 Notes) | Series Z Preferred Stock
Debt Instrument [Line Items]
Warrants to purchase | shares		219,994				219,994
2.75% Convertible Senior Notes due 2020 (2013 Notes)
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 49,600,000		$ 115,000,000	$ 1,000			$ 1,000
Interest rate			2.75%
Debt instrument, maturity date			Dec. 01, 2020
Debt instrument, convertible, conversion rate							12.21225
Debt instrument, convertible, conversion price | $ / shares				$ 81.88			$ 81.88
Debt issuance cost			$ 488,000
Debt instrument, term			7 years
Repurchase of notes description							On and after September 1, 2020 until the close of business on the business day immediately preceding the maturity date, holders may convert all or a portion of their 2013 Notes at any time, regardless of the foregoing circumstances.
Debt instrument, interest payment terms							The Company pays 2.75% interest per annum on the principal amount of the 2013 Notes semi-annually in arrears in cash on June 1 and December 1 of each year.
Carrying value of equity component of convertible debt - not including deduction for issuance costs				$ 31,300,000			$ 31,300,000
Debt instrument, repurchased face amount										35,000,000
Debt instrument, repurchase amount										10,000,000
Gain on extinguishment of debt										$ 18,300,000
2.75% Convertible Senior Notes due 2020 (2013 Notes) | Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair value of liability component upon issuance				$ 79,700,000			$ 79,700,000
Debt instrument, principal amount				8.69%			8.69%
2.75% Convertible Senior Notes due 2020 (2013 Notes) | During Any Fiscal Quarter Commencing After March 31, 2014
Debt Instrument [Line Items]
Debt instrument, convertible, terms of conversion feature							During any fiscal quarter commencing after March 31, 2014, if, for at least 20 trading days (whether or not consecutive) during the 30 consecutive trading day period ending on the last trading day of the immediately preceding fiscal quarter, the last reported sale price of the Company’s common stock on such trading day is greater than or equal to 130% of the applicable conversion price on such trading day
Threshold consecutive trading days			30 days
2.75% Convertible Senior Notes due 2020 (2013 Notes) | During The Five Consecutive Business Day Period
Debt Instrument [Line Items]
Debt instrument, convertible, terms of conversion feature							During the five consecutive business day period immediately following any ten consecutive trading day period (the “measurement period”) in which, for each trading day of that measurement period, the trading price per $1,000 principal amount of notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock on such trading day and the applicable conversion rate on such trading day
Debt instrument, redemption price, percentage			100.00%
Threshold consecutive trading days			10 days
Number of business day period			5 days
2.75% Convertible Senior Notes due 2020 (2013 Notes) | On and after September 1, 2020 until the close of business
Debt Instrument [Line Items]
Debt instrument, convertible, terms of conversion feature							Upon the occurrence of specified corporate transactions.
2.75% Convertible Senior Notes due 2020 (2013 Notes) | Maximum | During The Five Consecutive Business Day Period
Debt Instrument [Line Items]
Convertible, threshold percentage of stock price trigger			98.00%
2.75% Convertible Senior Notes due 2020 (2013 Notes) | Minimum | During Any Fiscal Quarter Commencing After March 31, 2014
Debt Instrument [Line Items]
Threshold trading days | d			20
Convertible, threshold percentage of stock price trigger			130.00%
2.75% Convertible Senior Unsecured Exchange Notes Due 2020 (2017 Exchange Notes)
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 1,000
Interest rate	2.75%
Debt instrument, maturity date	Dec. 01, 2020
Debt instrument, convertible, terms of conversion feature							If Company elects, or is deemed to have elected, to pay any Interest Make-Whole Payment by delivering shares of common stock, the number of shares of common stock a converting holder of 2017 Exchange Notes will receive for each $1,000 principal amount of 2017 Exchange Notes will be the number of shares equal to the amount of the Interest Make-Whole Payment to be paid to such holder, divided by the product of (x) 98% and (y) the simple average of the daily volume-weighted average price of the common stock for the five trading days ending on and including the trading day immediately preceding the conversion date. Subject to compliance with certain conditions, the Company has the right, or the Mandatory Conversion Right, to, at its option, mandatorily convert all of the 2017 Exchange Notes if the daily volume-weighted average price of the common stock is equal to or greater than 60.0% of the applicable conversion price of the 2017 Exchange Notes for at least 20 Daily VWAP Trading Days (as defined in the 2017 Indenture) (whether or not consecutive) during any 30 consecutive Daily VWAP Trading Day period (including the last trading day of such period).
Debt instrument, convertible, conversion rate	66.6667
Debt instrument, convertible, conversion price | $ / shares	$ 15.00
Debt instrument, redemption price, percentage	100.00%
Repurchase of notes description							The 2017 Exchange Notes are convertible at any time prior to the close of business on the business day immediately preceding the maturity date, at the option of the holders, into (i) shares of the Company’s common stock, plus (ii) a cash payment equal to $150 for each $1,000 principal amount of 2017 Exchange Notes converted, or the Additional Conversion Payment, subject to certain adjustments. For conversions prior to September 1, 2018 and prior to the Company’s election to exercise its Mandatory Conversion Right (as defined in the 2017 Indenture), the Company will make an interest make-whole payment to a converting holder for each $1,000 principal amount of 2017 Exchange Notes being converted, or the Interest Make-Whole Payment. The Company may pay any Interest Make-Whole Payment either in cash or in shares of common stock, at the Company’s election. If the Company elects to pay any Interest Make-Whole Payment in cash it will pay cash in an amount equal to the Interest Make-Whole Payment.
Debt instrument, interest payment terms							The 2017 Exchange Notes bear interest at a fixed rate of 2.75% per year, payable semi-annually in arrears on June 1 and December 1 of each year, beginning June 1, 2017. Interest on the 2017 Exchange Notes accrues from December 1, 2016. The 2017 Exchange Notes will mature on December 1, 2020, unless earlier repurchased, redeemed or converted.
Gain on extinguishment of debt							$ 12,300,000
Debt instrument convertible cash payment for each $1000 principal amount	$ 150,000
Debt instrument redemption period start date	Dec. 01, 2019
Net carrying value, net of transaction costs	$ 40,200,000
Direct costs and fees incurred to issue notes							1,500,000
Aggregate fair value of notes	$ 26,400,000			$ 17,000,000			17,000,000
Debt instrument, principal balance converted into common stock							$ 9,200,000
Debt instrument, principal balance converted into common stock, shares | shares							784,237
Common stock issued for interest make-whole payment | shares							173,705
Aggregate additional conversion payment							$ 1,400,000
2.75% Convertible Senior Unsecured Exchange Notes Due 2020 (2017 Exchange Notes) | During Five Trading Days
Debt Instrument [Line Items]
Threshold trading days | d	5
Convertible, threshold percentage of stock price trigger	98.00%
2.75% Convertible Senior Unsecured Exchange Notes Due 2020 (2017 Exchange Notes) | During Thirty Consecutive Trading Days
Debt Instrument [Line Items]
Threshold consecutive trading days	30 days
2.75% Convertible Senior Unsecured Exchange Notes Due 2020 (2017 Exchange Notes) | Minimum | During Twenty Trading Days
Debt Instrument [Line Items]
Threshold trading days | d	20
Convertible, threshold percentage of stock price trigger	60.00%