Accounts Payable and Accrued Liabilities - Summary of Components of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts payable	$ 3,166	$ 12,236
Accrued rebates	12,261	5,648
Accrued compensation and benefits	3,814	3,472
Accrued acquisition costs	318	2,311
Accrued returns	715	915
Accrued royalties	159	488
Accrued clinical trial costs	464	234
Accrued legal	70	216
Accrued other	572	629
Total accounts payable and accrued expenses	$ 21,539	$ 26,149