Accounts Payable and Accrued Liabilities - Summary of Components of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts payable	$ 10,056	$ 12,236
Accrued rebates	7,056	5,648
Accrued compensation and benefits	1,757	3,472
Accrued acquisition costs	1,412	2,311
Accrued returns	1,293	915
Accrued royalties	503	488
Accrued clinical trial costs	317	234
Accrued legal	227	216
Accrued other	607	629
Total accounts payable and accrued liabilities	$ 23,228	$ 26,149