Revenue from Contracts with Customers - Impact of Adoption of Asc 606 on Company's Condensed Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	$ 12,175	$ 8,744	$ 23,456	$ 38,220
Net loss attributable to common stockholders	(9,770)	(14,879)	(20,479)	33,446
Product Sales [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	10,766	7,886	20,604	15,680
Product Royalty Revenues [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	1,386	$ 613	1,826	2,273
Contract Revenues [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	23		1,026	$ 20,000
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	12,152		23,243
Net loss attributable to common stockholders	(9,793)		(20,692)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Product Sales [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	10,766		20,604
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Product Royalty Revenues [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	1,386		1,826
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Contract Revenues [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues			813
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	23		213
Net loss attributable to common stockholders	23		213
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Contract Revenues [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues	$ 23		$ 213