Summary of Change in Reserves for Discounts and Allowances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	$ 28,510	$ 8,587
Provision	68,987	48,614
Payments/credits	(45,994)	(28,691)
Ending balance	51,503	28,510
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	1,378	995
Provision	9,698	12,284
Payments/credits	(10,488)	(11,901)
Ending balance	588	1,378
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	24,276	6,959
Provision	44,749	28,420
Payments/credits	(24,287)	(11,103)
Ending balance	44,738	24,276
Prompt Pay [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	538	169
Provision	4,897	2,624
Payments/credits	(3,929)	(2,255)
Ending balance	1,506	538
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	2,318	464
Provision	9,643	5,286
Payments/credits	(7,290)	(3,432)
Ending balance	$ 4,671	$ 2,318