Fair Value of Financial Instruments (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Financial liabilities:
Financial liabilities fair value	$ 106,800	$ 102,000
MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	38,100
Deerfield Credit Facility
Financial liabilities:
Financial liabilities fair value		11,400
June 2020 Note
Financial liabilities:
Financial liabilities fair value	2,100
Senior Convertible Notes
Financial liabilities:
Financial liabilities fair value	3,300	17,500
December 2020 Note
Financial liabilities:
Financial liabilities fair value	1,900
Milestone Rights Liability
Financial liabilities:
Financial liabilities fair value	19,400	18,100
Mann Group Notes
Financial liabilities:
Financial liabilities fair value	42,000	55,000
Carrying Value
Financial liabilities:
Financial liabilities fair value	127,600	111,400
Carrying Value | MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	38,800
Carrying Value | Deerfield Credit Facility
Financial liabilities:
Financial liabilities fair value		11,300
Carrying Value | June 2020 Note
Financial liabilities:
Financial liabilities fair value	2,500
Carrying Value | Senior Convertible Notes
Financial liabilities:
Financial liabilities fair value	5,000	19,100
Carrying Value | December 2020 Note
Financial liabilities:
Financial liabilities fair value	2,400
Carrying Value | Milestone Rights Liability
Financial liabilities:
Financial liabilities fair value	8,900	8,900
Carrying Value | Mann Group Notes
Financial liabilities:
Financial liabilities fair value	70,000	72,100
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	106,800	102,000
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | MidCap Credit Facility
Financial liabilities:
Financial liabilities fair value	38,100
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Deerfield Credit Facility
Financial liabilities:
Financial liabilities fair value		11,400
Estimate of Fair Value Measurement | June 2020 Note | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	2,100
Estimate of Fair Value Measurement | Senior Convertible Notes | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	3,300	17,500
Estimate of Fair Value Measurement | December 2020 Note | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	1,900
Estimate of Fair Value Measurement | Milestone Rights Liability | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	19,400	18,100
Estimate of Fair Value Measurement | Mann Group Notes | Fair Value, Inputs, Level 3
Financial liabilities:
Financial liabilities fair value	$ 42,000	$ 55,000