Summary of Significant Accounting Principles - Total Net Product Sales from External Customers by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net product sales	$ 49,003	$ 67,303	$ 64,197	$ 59,384	$ 51,712	$ 43,674	$ 36,014	$ 26,973	$ 239,887	$ 158,373	$ 48,546
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net product sales									214,590	143,354	42,290
BRAZIL
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net product sales									14,998	11,089	6,019
Outside Of The United States Besides Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net product sales									$ 10,299	$ 3,930	$ 237