Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts payable	$ 2,175	$ 3,166
Accrued rebates	24,625	12,261
Accrued compensation and benefits	4,662	3,814
Accrued acquisition costs	9,970	318
Accrued returns	1,477	715
Accrued royalties	419	159
Accrued clinical trial costs	0	464
Accrued legal	556	70
Accrued interest expense	1,508	0
Accrued regulatory expenses	282	0
Accrued other	871	572
Total accounts payable and accrued liabilities	$ 46,545	$ 21,539