Significant Accounting Policies - Additional Information (Detail)	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2017 USD ($)	Jan. 31, 2012	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) Segment Customer shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Jan. 20, 2017 USD ($)	Nov. 30, 2015 USD ($)	Jun. 30, 2015 Tranche	Mar. 30, 2015 USD ($)	Mar. 05, 2015 USD ($)	Dec. 31, 2014 shares	May 31, 2014 USD ($)	Dec. 31, 2012 USD ($)
Significant Accounting Policies [Line Items]
Sales discount percentage				2.00%
Trade receivables, credit period				30 days
Number of tranches for private placement transaction | Tranche									2
Deferred tax assets					$ 11,082,000
Accounts receivable written off				$ 0
Gain (loss) on change in fair value of derivative liabilities					$ 8,170,000	$ (1,106,000)
Warrants outstanding | shares				0	0
Number of operating segments | Segment				1
Warrants Issued October 2009
Significant Accounting Policies [Line Items]
Gain (loss) on change in fair value of derivative liabilities						$ 100,000
Warrants outstanding | shares				0	0							8,087,388
Warrants exercised | shares						1,844,585
Warrants expired | shares						6,242,803
Embedded Derivative Financial Instruments | BioPharma Debt
Significant Accounting Policies [Line Items]
Maximum repayment of future revenue and receivables														$ 150,000,000
Fair value of embedded derivative liability				$ 0	$ 0
Gain (loss) on change in fair value of derivative liabilities				$ 0	$ 5,500,000
Embedded Derivative Financial Instruments | BioPharma Debt | Minimum
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term				2 years 3 months 18 days	2 years 4 months 24 days
Derivative liability fair value assumption, coupon rate				5.80%	8.10%
Derivative liability fair value assumptions, market yields				10.20%	11.90%
Embedded Derivative Financial Instruments | BioPharma Debt | Maximum
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term				4 years 3 months 18 days	5 years
Derivative liability fair value assumption, coupon rate				10.80%	11.10%
Derivative liability fair value assumptions, market yields				18.40%	18.40%
Preferred Stock Purchase Option | Second Private Placement
Significant Accounting Policies [Line Items]
Gain (loss) on change in fair value of derivative liabilities						$ (900,000)
Derivative liability at fair value										$ 1,800,000	$ 900,000
Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Number of customers | Customer				3
Customer A | Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				33.00%	37.00%
Customer A | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				21.00%	33.00%
Customer B | Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				28.00%	30.00%
Customer B | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				41.00%	16.00%
Customer C | Gross Product Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				27.00%	28.00%
Customer C | Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage				27.00%	47.00%
2012 Notes
Significant Accounting Policies [Line Items]
Aggregate principal amount of notes	$ 15,000,000
Aggregate principal amount redeemed	100,000
2017 Notes
Significant Accounting Policies [Line Items]
Aggregate principal amount of notes				$ 30,000,000
Convertible senior notes, discount				$ 1,200,000
Convertible Debt | 2012 Notes
Significant Accounting Policies [Line Items]
Aggregate principal amount of notes					$ 15,107,000
Convertible senior notes, discount					0
Note, expected term		24 months		24 months
Convertible senior notes, principal amount purchase	$ 15,000,000		$ 15,000,000					$ 16,200,000
Convertible senior notes, aggregate principal amount redeemed			$ 100,000	$ 100,000
Convertible senior notes, outstanding amount				0
Convertible Debt | 2017 Notes
Significant Accounting Policies [Line Items]
Convertible senior notes, discount				1,000,000			$ 1,200,000
Convertible Debt | 2014 Notes and 2015 Notes
Significant Accounting Policies [Line Items]
Gain (loss) on change in fair value of derivative liabilities				0
Convertible Debt | 2014 Notes
Significant Accounting Policies [Line Items]
Convertible senior notes, discount													$ 27,900,000
Gain (loss) on change in fair value of derivative liabilities					2,100,000
Derivative liability at fair value													$ 3,500,000
Convertible Debt | 2015 Notes
Significant Accounting Policies [Line Items]
Convertible senior notes, discount								3,800,000
Gain (loss) on change in fair value of derivative liabilities					600,000
Derivative liability at fair value								$ 500,000
ASU No. 2016-09
Significant Accounting Policies [Line Items]
Excess tax benefits (deficiencies) on stock-based awards				$ 1,300,000	$ (400,000)
Deferred tax assets						1,600,000
ASU No. 2016-09 | Scenario, Previously Reported
Significant Accounting Policies [Line Items]
Excess tax benefits (deficiencies) on stock-based awards						700,000
ASU No. 2016-09 | Cumulative-effect adjustment
Significant Accounting Policies [Line Items]
Excess tax provision on stock-based awards						$ (700,000)