Accounts Payable and Accrued Liabilities - Summary of Components of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts payable	$ 4,167	$ 3,166
Accrued rebates	19,584	12,261
Accrued compensation and benefits	3,443	3,814
Accrued acquisition costs	10,000	318
Accrued returns	830	715
Accrued royalties	464	159
Accrued clinical trial costs		464
Accrued legal	391	70
Accrued regulatory expenses	229
Accrued other	1,654	572
Total accounts payable and accrued liabilities	$ 40,762	$ 21,539