Organization and Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts
Allowance for doubtful accounts	$ 0
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning	2,290	$ 1,903
Provision related to current period sales	7,627	6,346
Adjustment related to prior period sales	(362)	509
Credit or payments made during the period	(8,027)	(6,468)
Balance at the end	$ 1,528	2,290
Equity interest	85.00%
Chargebacks, Discounts and Fees
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning	$ 992	779
Provision related to current period sales	6,402	5,193
Adjustment related to prior period sales	(81)	(127)
Credit or payments made during the period	(6,938)	(4,853)
Balance at the end	375	992
Government and Other Rebates
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning	352	377
Provision related to current period sales	704	580
Adjustment related to prior period sales	168	75
Credit or payments made during the period	(932)	(680)
Balance at the end	292	352
Returns
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning	946	747
Provision related to current period sales	521	573
Adjustment related to prior period sales	(449)	561
Credit or payments made during the period	(157)	(935)
Balance at the end	$ 861	$ 946