Liability Related to Sale of Future Royalties - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Feb. 24, 2012	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability Related to Sale of Future Royalties [Line Items]
Non-cash royalty revenue related to sale of future royalties		$ 8,066	$ 7,692	$ 21,367	$ 22,341
Non-cash interest expense on liability related to sale of future royalties		$ 4,471	$ 4,902	$ 13,535	$ 14,929
Annual interest rate				17.00%
Purchase and Sale Agreement with RPI [Member]
Liability Related to Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights	$ 124,000
Transaction costs related to sale of potential future royalties	$ 4,400