Gross-to-Net (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	$ 41,911	$ 14,266	$ 5,587
Provision	160,200	169,138	69,712
Charges processed	(173,569)	(141,493)	(61,033)
Valuation allowances and reserves balance, end of year	28,542	41,911	14,266
Returns
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	2,310	934	674
Provision	6,034	3,568	1,724
Charges processed	(7,023)	(2,192)	(1,464)
Valuation allowances and reserves balance, end of year	1,321	2,310	934
Chargebacks & Rebates
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	35,881	12,450	4,552
Provision	148,000	160,556	65,713
Charges processed	(159,809)	(137,125)	(57,815)
Valuation allowances and reserves balance, end of year	24,072	35,881	12,450
Discounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	3,303	792	345
Provision	4,398	4,667	2,201
Charges processed	(6,737)	(2,156)	(1,754)
Valuation allowances and reserves balance, end of year	964	3,303	792
Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	417	90	16
Provision	1,768	347	74
Charges processed	0	(20)	0
Valuation allowances and reserves balance, end of year	$ 2,185	$ 417	$ 90