Schedule II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for chargebacks
Movement in valuation and qualifying accounts
Balance at beginning of period	$ 1,314	$ 816	$ 779
Additions charged to costs and expenses	12,135	8,565	10,146
Deductions and Payments	(9,299)	(8,067)	(10,109)
Balance at end of period	4,150	1,314	816
Allowance for cash discounts
Movement in valuation and qualifying accounts
Balance at beginning of period	551	337	171
Additions charged to costs and expenses	3,801	3,519	1,814
Deductions and Payments	(3,654)	(3,305)	(1,648)
Balance at end of period	698	551	337
Savings offers
Movement in valuation and qualifying accounts
Balance at beginning of period	11,288	7,168	2,070
Additions charged to costs and expenses	69,540	71,303	30,978
Deductions and Payments	(64,038)	(67,183)	(25,880)
Balance at end of period	16,790	11,288	7,168
Reserve for wholesaler fees
Movement in valuation and qualifying accounts
Balance at beginning of period	4,249	2,345	509
Additions charged to costs and expenses	17,225	17,414	8,244
Deductions and Payments	(16,460)	(15,510)	(6,408)
Balance at end of period	5,014	4,249	2,345
Reserve for returns
Movement in valuation and qualifying accounts
Balance at beginning of period	5,157	2,711	1,157
Additions charged to costs and expenses	3,299	3,803	1,792
Deductions and Payments	(3,334)	(1,357)	(238)
Balance at end of period	5,122	5,157	2,711
Rebates
Movement in valuation and qualifying accounts
Balance at beginning of period	7,763	4,008	544
Additions charged to costs and expenses	17,355	18,746	7,837
Deductions and Payments	(19,009)	(14,991)	(4,373)
Balance at end of period	$ 6,109	$ 7,763	$ 4,008