Summary of Significant Accounting Policies - Chargebacks, Rebates, Administrative Fees and Other, and Sales Returns (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash and cash equivalents	$ 72,181	$ 184,090	$ 144,804
Working capital	(494,700)
Accumulated deficit	(590,665)		(333,938)
Operating income (loss)	(246,918)	(65,483)
Net (Loss)	$ (256,727)	(82,181)
Payment terms, period	90 days
Gain (loss) on disposition of business	$ 35,900
Restricted cash	$ 730	785	$ 800
Extended chargeback period	84 days
Chargeback provision	$ 156,275	$ 205,394
Sales chargebacks as percentage of gross sales	36.40%	44.80%
Gross sales (1)	$ 429,376	$ 458,641
Chargeback reserves	1.99%
Potential increase in chargeback expense based on sensitivity analysis	$ 400
Potential decrease in chargeback expense based on sensitivity analysis	700
Rebates, administrative and other fees	$ 52,844	$ 64,264
Rebates, administrative and other fees as a percentage of gross sales	12.30%	14.00%
Rebates, administrative and other fees	1.99%
Potential increase in rebates, administrative and other fees expense based on sensitivity analysis	$ 17
Potential decrease in rebates, administrative and other fees expense based on sensitivity analysis	100
Sales returns	$ 4,259	$ 11,902
Change in ratio of direct to indirect sales for sales return reserve used in sensitivity analysis	1.00%	2.60%
Returns, change in average return time	7 months 6 days
Potential increase in sales returns expense based on sensitivity analysis	$ 200
Potential decrease in sales returns expense based on sensitivity analysis	$ 600
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Standard chargeback period	28 days
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Standard chargeback period	42 days