Revenue - Activities and Ending Reserve Balances for Each Significant Category of Discounts and Allowances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31	$ 87,147
Provision related to sales made in:
Current period	316,807	$ 97,162
Prior period	(9,554)
Payments and customer credits issued	(302,175)	(53,155)
Balance at June 30	92,225	44,007
Chargebacks and Discounts for Prompt Payment
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31	35,159
Provision related to sales made in:
Current period	208,917	65,726
Prior period	(159)
Payments and customer credits issued	(219,040)	(42,368)
Balance at June 30	24,877	23,358
Rebates
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31	27,494
Provision related to sales made in:
Current period	49,245	8,593
Prior period	(3,287)
Payments and customer credits issued	(31,732)	(1,095)
Balance at June 30	41,720	7,498
Other Fees, Co-pay Assistance and Returns
Accounts Notes And Loans Receivable [Line Items]
Balance at December 31	24,494
Provision related to sales made in:
Current period	58,645	22,843
Prior period	(6,108)
Payments and customer credits issued	(51,403)	(9,692)
Balance at June 30	$ 25,628	$ 13,151