Restatement of the Consolidated Financial Statements - Restatement of Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales	$ 92,586	$ 86,959	$ 95,417	$ 84,149	$ 87,857	$ 84,000	$ 80,487	$ 68,795	$ 359,111	$ 321,139	$ 221,712
Cost of sales									36,386	35,219	30,938
Gross profit	82,183	79,604	86,147	74,791	78,455	74,697	72,002	60,766	322,725	285,920	190,774
Operating expenses:
Selling, general and administrative									258,528	220,119	173,412
Research and development expenses									15,765	17,900	14,341
Amortization of intangible assets									1,034	1,678	2,137
Operating (loss) income									(3,924)	46,223	884
Other expense, net											(339)
(Loss) income before income tax provision									(3,397)	45,088	545
Income tax provision (expense) benefit	(27,497)	(650)	13	1,552	(9,537)	30,436	(980)	(280)	(26,582)	19,639	(155)
Net (loss) income	$ (36,224)	$ (178)	$ 1,804	$ 4,619	$ 4,276	$ 44,051	$ 10,402	$ 5,998	$ (29,979)	$ 64,727	$ 390
Net income (loss) per common share - basic (in dollars per share)	$ (0.34)	$ 0	$ 0.02	$ 0.04	$ 0.04	$ 0.41	$ 0.10	$ 0.06	$ (0.28)	$ 0.61	$ 0.00
Net income (loss) per common share - diluted (in dollars per share)	$ (0.34)	$ 0	$ 0.02	$ 0.04	$ 0.04	$ 0.37	$ 0.09	$ 0.05	$ (0.28)	$ 0.56	$ 0
Weighted average shares outstanding - basic (in shares)									105,596,256	106,121,810	105,928,348
Weighted average shares outstanding - diluted (in shares)									105,596,256	116,113,736	112,645,640
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales						$ 84,573	$ 76,412	$ 72,607			$ 245,015
Cost of sales											32,407
Gross profit						74,974	67,781	63,864			212,608
Operating expenses:
Selling, general and administrative											179,997
Research and development expenses											12,038
Amortization of intangible assets											2,127
Operating (loss) income											18,446
Other expense, net											(339)
(Loss) income before income tax provision											18,107
Income tax provision (expense) benefit						4,384	1,005	(1,713)			(6,133)
Net (loss) income						$ 17,457	$ 8,069	$ 4,327			$ 11,974
Net income (loss) per common share - basic (in dollars per share)						$ 0.16	$ 0.08	$ 0.04			$ 0.11
Net income (loss) per common share - diluted (in dollars per share)						$ 0.15	$ 0.07	$ 0.04			$ 0.11
Weighted average shares outstanding - basic (in shares)											105,928,348
Weighted average shares outstanding - diluted (in shares)											112,441,709
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales											$ (23,303)
Cost of sales											(1,469)
Gross profit											(21,834)
Operating expenses:
Selling, general and administrative											(6,585)
Research and development expenses											2,303
Amortization of intangible assets											10
Operating (loss) income											(17,562)
Other expense, net											0
(Loss) income before income tax provision											(17,562)
Income tax provision (expense) benefit											5,978
Net (loss) income											(11,584)
Cash Revenue | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales											(14,725)
Cost of sales											0
Gross profit											(14,725)
Operating expenses:
Selling, general and administrative											0
Research and development expenses											0
Amortization of intangible assets											0
Operating (loss) income											(14,725)
Other expense, net											0
(Loss) income before income tax provision											(14,725)
Income tax provision (expense) benefit											0
Net (loss) income											(14,725)
GPO Fees | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales											(4,487)
Cost of sales											0
Gross profit											(4,487)
Operating expenses:
Selling, general and administrative											(4,487)
Research and development expenses											0
Amortization of intangible assets											0
Operating (loss) income											0
Other expense, net											0
(Loss) income before income tax provision											0
Income tax provision (expense) benefit											0
Net (loss) income											0
Revenue Related | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales											(4,091)
Cost of sales											(1,469)
Gross profit											(2,622)
Operating expenses:
Selling, general and administrative											(1,744)
Research and development expenses											0
Amortization of intangible assets											0
Operating (loss) income											(878)
Other expense, net											0
(Loss) income before income tax provision											(878)
Income tax provision (expense) benefit											0
Net (loss) income											(878)
Other | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales											0
Cost of sales											0
Gross profit											0
Operating expenses:
Selling, general and administrative											(354)
Research and development expenses											2,303
Amortization of intangible assets											10
Operating (loss) income											(1,959)
Other expense, net											0
(Loss) income before income tax provision											(1,959)
Income tax provision (expense) benefit											5,978
Net (loss) income											$ 4,019