Summary of Change in Reserves for Discounts and Allowances (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	$ 70,466	$ 50,970
Provision	38,738	22,027
Payments/credits	(26,296)	(17,128)
Ending balance	82,908	55,869
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	799	2,281
Provision	2,437	2,085
Payments/credits	(2,906)	(3,969)
Ending balance	330	397
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	60,506	41,771
Provision	24,140	14,907
Payments/credits	(16,563)	(9,108)
Ending balance	68,083	47,570
Prompt Pay [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	2,798	1,949
Provision	2,950	1,844
Payments/credits	(2,645)	(1,432)
Ending balance	3,103	2,361
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	6,363	4,969
Provision	9,211	3,191
Payments/credits	(4,182)	(2,619)
Ending balance	$ 11,392	$ 5,541